voucher photography using digital compact cameras · 2 although it may sound paradoxical,...

Click here to load reader

Post on 01-Aug-2020

1 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Photographing Moths

    Voucher Photography Using Digital Compact Cameras

    Chris Harlow, February 2005

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (1)

    Contents

    Preface .....................................................................................................................................2 Introduction .........................................................................................................................3

    The Rise of Digital.........................................................................................................................3 Digital vs. Film ..............................................................................................................................3 Digital Compact Cameras..............................................................................................................4

    Depth of Field...................................................................................................................4 Magnification....................................................................................................................5

    Other Advantages of Digital .........................................................................................................6 Choosing a Camera........................................................................................................................6

    General Principles.................................................................................................................8 Voucher Photographs ...................................................................................................................8

    ‘Pure’ Voucher Photographs .................................................................................................8 Location.........................................................................................................................................9 Photographer’s Grey Card .......................................................................................................... 10 Camera Support .......................................................................................................................... 10 Positioning Moths ....................................................................................................................... 12 Persuading Moths to Co-operate ................................................................................................ 13 Documentation ........................................................................................................................... 15 Organising, Backing-up and Archiving Photographs ................................................................ 17

    Organisation................................................................................................................... 17 Backing-Up and Archiving .................................................................................................. 17

    Using the Camera ................................................................................................................19 Take Control of the Camera ........................................................................................................ 19 Macro Mode................................................................................................................................ 21 Reviewing Photographs .............................................................................................................. 22

    The Histogram................................................................................................................ 22 Focusing ...................................................................................................................................... 23

    Manual Focus.................................................................................................................. 24 Using The Self-Timer........................................................................................................ 24 Awkward Focusing Situations.............................................................................................. 25 BSS (Best Shot Selector) .................................................................................................... 26

    Depth of Field.............................................................................................................................. 26 Aperture ....................................................................................................................... 27 Focal Length and Distance to Subject..................................................................................... 28

    Consistent Colour (White Balance) ............................................................................................ 29 Manual White Balance....................................................................................................... 30

    Exposure...................................................................................................................................... 31 Aperture-priority Mode for Voucher Photography .................................................................... 32 Shutter-priority Mode for Field Photography........................................................................... 32 Sensitivity (ISO) .............................................................................................................. 33 Metering ....................................................................................................................... 34 Exposure Compensation .................................................................................................... 34 Advanced Exposure Control ............................................................................................... 35

    Lighting ....................................................................................................................................... 36 Coping With Bright Conditions ........................................................................................... 37 Coping with Dark Conditions.............................................................................................. 38

    Taking ‘Pure’ Voucher Photographs........................................................................................... 39 Photography with a Microscope................................................................................................. 41

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (2)

    Preface This article describes the use of digital compact cameras, and the Nikon Coolpix 990/995/4500 series in particular, for taking voucher photographs of moths. Although many of the techniques are also suitable for photographing moths in the field and for capturing aspects of moth behaviour, I have not concentrated on these. If you wish to learn more about this side of photography and particularly if you want to be inspired by what is possible, Roy Leverton’s book “Enjoying Moths” is the place to start.

    I am not an expert on moths, nor am I an expert photographer. However, I have been using a digital camera to photograph moths and other insects since 2001 and can therefore claim some experience. During this period I have made many mistakes and have had many disappointments. To try and overcome these I have experimented with a variety of different techniques. Some have proven successful and others less so, but the overall result has been that my success rate has improved with fewer mistakes and significantly more acceptable photographs. This article is an attempt to help others who might be faced with the same learning curve to achieve better results in a much shorter time.

    The Coolpix 950, 990, 995 and 4500 digital cameras have long been a favourite with macro photographers and naturalists - and for very good reason. All of them have excellent close-up performance, a flexible swivel lens design and comprehensive manual override capabilities. Although this article specifically refers to them, the principles should be directly transferable to any other digital compact camera that has equivalent functions.

    I only became interested in moths 2 years ago and at first blundered about in the dark, very much unsure about my identifications and the techniques involved. I would like to extend my gratitude to Bob Palmer, Mark Young and Roy Leverton, the county recorders for northeast Scotland, for their patience and generous help in answering my many, often naïve, questions and for shedding light on my confusion. Thanks are also due to Jon Clifton of ALS who has always been willing to help with advice and suggestions concerning mothing equipment and to Ian Kimber for his efforts with the UKMoths website (http://www.ukmoths.force9.co.uk/), which has been both a help and inspiration. Last but not least I must express gratitude to my wife Caroline who has not only tolerated my growing obsession but has given over part of her beloved polytunnel so that I can amuse myself by photographing moths. Negotiations over freezer space are still ongoing!

    Chris Harlow, January 2005 mailto:[email protected]

    Cover: Red Sword-grass (Xylena vetusta, left) and Sword-grass (Xylena exsoleta, right)

    © This article, and the images within it, is copyright of the author. Permission to use and redistribute it without charge is freely and willingly given provided that such use is solely for personal, educational or research purposes. Use, reproduction or transmittal by any means for commercial purposes is expressly forbidden without the written permission of the author.

    http://www.ukmoths.force9.co.uk/mailto:[email protected]

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (3)

    Introduction Throughout this document the term “Coolpix 4500 series” is used to describe the Nikon Coolpix 950, 990, 995 and 4500 cameras. Where reference is made to a single camera model this is given in full, e.g. “Nikon Coolpix 4500”

    The Rise of Digital In recent years advances in digital photography have made it increasingly easy to take good, clear photographs of moths. These technological improvements have been paralleled by the widespread use of e-mail and the Internet to make the distribution of digital photographs quick and easy. As a consequence, digital photography has become an effective means of communication between moth enthusiasts and a valuable link between the novice and the expert. It is now possible to catch a moth, photograph it, e-mail the photograph to the county recorder with a request for help and receive an informed reply within 24 hours or less. Posting an image to a forum of like-minded people such as the Yahoo UKMoths group1 often produces several responses in a matter of minutes. The moth can be safely retained in the meantime and then, once the replies have been received, released back into the wild or retained for further investigation.

    Photography is also an excellent way to build a ‘collection’ of moths without killing the specimens. Photographs can (and should) illustrate the moth in their natural resting position, making comparison with live moths much easier than it is with set specimens. In addition, in the digital world there are no real restrictions on how many photographs can be taken and therefore no reason why a collection should not encompass a wide range of individuals to display the variation within species. Photographs have a further advantage in that, unlike set specimens, the colours of the moths are preserved and do not fade.

    There are, of course, some significant disadvantages. For some moths a photograph is perfectly adequate for identification and verification, but for others it is not. In addition, some diagnostic features of moths are very difficult to photograph notably, but not exclusively, the hindwings. And of course, once a moth has been released back into the wild there is no way of going back to it to check features that were not visible in the photographs. Unlike a set specimen, the moth cannot then be dissected and is not available for examination at a later date. Photography should therefore be regarded as complementary to other techniques, such as setting and dissection, and not as a replacement. There is no reason why you should not do both!

    Digital vs. Film A year or two ago the photographic seemed to be divided into two almost irreconcilable camps. Film enthusiasts believed that digital photography was ridiculously expensive, inherently inferior and could never reproduce the subtleties of film. Converts to digital photography believed that their favoured technology was ultimately superior and that the ‘death’ of film was only a matter of time. I recall similar arguments being proposed when digital music in the form of the CD began to take over from analog tape and vinyl. In the end, although CD became pre-eminent, vinyl did not completely disappear and it has recently been enjoying something of a comeback. I believe that photography will follow a similar path. Digital will undoubtedly become the dominant force but film will continue to have a place for a long time to come.

    1 http://groups.yahoo.com/group/ukmoths/. You will need to sign up to Yahoo (which is free) in order to gain access to this group.

    http://groups.yahoo.com/group/ukmoths/

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (4)

    At the time of writing (February 2005), digital SLR cameras are finally penetrating the consumer market in numbers, with major manufacturers such as Canon, Nikon, Fuji and Olympus all firmly committed to the digital world. The purely technical capability of these cameras now equals, and in some cases exceeds, that of their 35mm film equivalents. Prices are falling fast, with each new model offering ever greater functionality and resolution for a lower price - although this is not to say they are now ‘affordable’ by all, especially when the cost of lenses is taken into account.

    In 2004 the global sales of digital cameras were estimated at a massive $24 billion. The bulk of these sales were not of digital SLRs, but of digital compact cameras. These have now reached a mass market and can genuinely be described as affordable. Models costing less than £300 offer a wealth of features and are more than capable of producing very high quality prints up to and above A4 size.

    Digital Compact Cameras When it comes to macro photography2, digital SLRs have more or less the same advantages and disadvantages as their 35mm film counterparts, although many of the current models which have a sensor smaller than 35mm offer a somewhat greater depth of field. As a consequence, the techniques used for macro photography with digital SLR cameras are essentially the same as those that are used for 35mm film cameras.

    Digital compact cameras are different. Their optics are constructed around very much smaller sensor sizes, producing a major advantage in terms of depth of field and an ability to focus close to the lens without the need for specialised add-on lenses. Not surprisingly, they have become very popular with entomologists and others who wish to explore the world of close-up photography at a reasonable cost. There are of course disadvantages, primarily associated with the lack of a true TTL (through the lens) viewfinder and a sometimes-quirky interface that varies from camera to camera. This can come as something as a shock to 35mm SLR users, but the key to success is to accept both the good and the bad and to learn how to use and get the best out of your equipment.

    Depth of Field Depth of field, by which we mean the zone of acceptable sharpness, is inherently greater in a digital compact camera than in a 35mm SLR and sometimes dramatically so. For digital cameras, the depth of field offered by a particular aperture is equivalent to the same aperture in a 35mm camera multiplied by the focal length equivalence ratio between the two. For most digital compact cameras this focal length equivalence ratio is usually between 4 and 5, leading to aperture equivalents of up to f64 in 35mm terms.

    The Nikon Coolpix 4500 has a focal length equivalence ratio of 4.84. This means that the depth of field provided by its aperture range of f2.6 to f10.3 is equivalent to an aperture range of

    approximately f12 to f50 on a 35mm SLR.

    The bad news is that an increased depth of field makes it more difficult to produce an out of focus background - which provides a pleasing, artistic feel to photographs by emphasising the subject that is in focus. This is not an insurmountable hurdle, as backgrounds can easily be blurred artificially using software. However, be warned that the inverse is not true: no amount of software manipulation or sharpening can rescue a blurred photograph where the detail was never captured in the first place!

    2 Although it may sound paradoxical, photographers use the term ‘macro photography’ to describe the close-up photography of small objects. The term ‘microphotography’ is used for photographs taken with a microscope.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (5)

    Original

    Background blurred with software

    Early Thorn (Selenia dentaria) f7.7 (equivalent to f37 in 35mm terms).

    Magnification The small-scale optics of digital compact cameras means that it is possible to focus close to the lens and almost all feature a ‘macro’ mode to enable this capability. Exactly how close you can get varies from camera to camera, but the Coolpix 4500 series cameras are among the best in the field in this respect. They allow focusing as close as 2cm from the lens. However, distance from the lens is not the only factor that affects magnification and the zoom setting (focal length) of the lens must also be taken into consideration. In this context it should be borne in mind that for digital compact cameras the closest focus distance claimed by the manufacturer can only be used over a limited part of the camera’s zoom range.

    A far better measure of macro capability is the size of the smallest object that can fill the frame, i.e. the minimum possible field of view. Unfortunately, manufacturers do not normally quote this figure and it has to be determined experimentally. For the Nikon Coolpix 4500 the minimum field of view is of the order of 18mm x 13.5mm – about the size of an average noctuid moth at rest and quite adequate for successfully photographing most micro-moths.

    How does this compare with 35mm photography? The macro capability of 35mm macro lenses is expressed as the ratio between the size of the subject on the film and the size of the object in real life. A very good 35mm macro lens capable of life-size (1:1) magnification will therefore have a field of view of approximately 36mm x 24mm, twice that of the Coolpix 4500 and therefore half of the magnification.

    However, the above is an over-simplification, as we must also take into account the size and resolution of the sensor and the effect that these have on the quality of the photograph when it is enlarged and printed. If we use the generally accepted figure of 300ppi3 as the optimum resolution for high-quality printed digital images, it follows that even with a little cropping the 2272 x 1704 pixel images produced by the Nikon Coolpix 4500 are capable of producing top quality 7” x 5” prints. Starting from a 18mm x 13.5mm field of view, this means that such prints will illustrate moths at approximately 10x life-size. To achieve the same printed magnification a 35mm photograph from a 1:1 macro lens would need to be enlarged to 14” x 10”. So even when we take the sensor size and resolution into account, the magnification offered by the Nikon Coolpix 4500 is effectively twice that of a 35mm SLR with a 1:1 macro lens.

    3 ppi stands for pixels per inch and is the number of pixels in the photograph that are used to construct one inch in the printed image. This should not be confused with dpi, which stands for dots per inch and refers to the number of ink droplets that are used to make up one inch of the print.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (6)

    Other Advantages of Digital Quite apart from the depth of field and close focus possibilities offered by digital compact cameras and the Coolpix 4500 series in particular, we must not forget the inherent advantages of digital photography. The most obvious of these is that once the initial investment in the camera and memory card(s) has been made, there are no film or processing costs. The cost per print from digital ‘negatives’ is broadly the same as for 35mm film.

    With digital cameras you can take as many photographs as you like and keep only the best. Taking lots of photographs in the hope that one will turn out to be good will not guarantee success or make you a better photographer - far from it. It will, on the other hand, give you the freedom to try different techniques and compositions, bracket exposures and generally experiment without worrying about how much film you are using.

    Rather more importantly, digital cameras allow you to see the results of your efforts straight away. You will be able to spot the errors early, try again and learn from your mistakes without having to wait for your prints or slides to be returned from the developers. For me this has been by far and away the greatest advantage of digital photography.

    Choosing a Camera The Nikon Coolpix 4500 series cameras have long been a favourite with macro photographers and naturalists - and for very good reason. All of them can focus as close as 2cm from the lens, have a flexible swivel lens design and offer comprehensive manual override capabilities. The 28mm threaded lens and the ability to add other lenses or connect the camera to other optical equipment such as microscopes and spotting scopes has also proved popular. The essential features of the different models are as follows:

    Model Release Date Close Focus Optical Zoom (35mm equiv)

    Resolution

    950 1999 2cm 3x: 38mm – 115mm 2 megapixel (1600 x 1200) 990 2000 2cm 3x: 38mm - 115mm 3 megapixel (2048 x 1536) 995 2001 2cm 4x: 38mm – 152mm 3 megapixel (2048 x 1536)

    4500 2002 2cm 4x: 38mm – 155mm 4 megapixel (2272 x 1704) No new camera has been added to this series since 2002 and, as far as I am aware, none is planned. The reason may be that the 4-megapixel resolution of the 4500 is close to the maximum that can be achieved by the small scale optics and that increasing the resolution would not in fact produce better quality images. This is, however, pure conjecture on my part.

    There has also been speculation on the Internet that the 4500 has been discontinued, although at the time of writing (February 2005) the model is still listed as current on the Nikon website and continues to be available new from several Internet sites in the UK. Both it and the older models are also widely available in the used camera market.

    If you would prefer to look for an alternative manufacturer or model, the key specifications are as follows:

    • Good close focus capability. This should ideally be of the order of 5cm or less if you want to photograph macro moths and 3cm or less if you want to photograph micro moths.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (7)

    • Separate aperture-priority and shutter-priority exposure modes. You need to be able to explicitly set the preferred aperture or shutter speed. Full manual control is advantageous but not critical. This is available on higher specification digital cameras.

    • Manual white balance. You need to be able to manually set the white balance against a neutral white or grey shade. This is available on many digital cameras.

    • A tripod mount. Supporting the camera is essential. The majority of digital cameras, with the exception of those that are unusually compact or thin, have a tripod mount.

    • Self-timer mode. This is very useful for reducing camera shake if the camera does not support the attachment of a shutter release cable. Most digital cameras have this facility.

    • A swivel lens or a flip-out and rotate LCD monitor. This is very useful if you don’t want to have to do contortions when you are photographing moths. Although the swivel lens design is now rare, flip-out and rotate monitors are available on many cameras.

    In addition to the above, cameras with a higher 35mm focal length equivalence ratio will produce a greater depth of field. To assess the depth of field capabilities of a camera, check the specifications and:

    1. Divide the 35mm equivalent focal length values by the actual focal length values for the camera. This is the focal length equivalence ratio.

    2. Multiply the quoted actual aperture range for the camera by the focal length equivalence ratio obtained in (a). This will give the 35mm aperture equivalents and hence a comparison of the depth of field capabilities.

    Example:

    35mm equivalent focal length range 24mm – 85mm, actual focal length range 6.1mm – 21.6mm. Focal length equivalence ratio = 3.93. Actual aperture range of f2.6 – f7.8 therefore has a depth of field equivalent to f10 – f30 on a 35mm camera.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (8)

    General Principles

    Voucher Photographs A voucher photograph is simply a photographic record of a moth that allows it to be clearly and unambiguously identified. To be of any value, the photograph must also be associated with the details of location, date and size (or scale) of the moth. Just as a set specimen is useless without a label, a voucher photograph is useless without the corresponding information.

    The ideal voucher photograph should:

    • Be correctly exposed. • Show the true colour of the moth. • Illustrate the diagnostic features of the moth. • Be properly documented.

    Of course, none of the above means that a voucher photograph cannot also have artistic merit or display the moth in a sympathetic, natural setting. If you look at the excellent photographs in Roy Leverton’s “Enjoying Moths” book you will see that the vast majority satisfy the criteria of a voucher photograph.

    ‘Pure’ Voucher Photographs I refer to a ‘pure’ voucher photograph as one that has been taken under controlled conditions against a plain, neutral background of known brightness and colour. This is the photographic equivalent of a set specimen, free from background distractions, that maximises the potential of the photograph to be used for identification purposes.

    Common Pug (Eupithecia vulgata vulgata)

    The pictures above are of the same specimen of Common Pug (Eupithecia vulgata vulgata). Both photographs are correctly exposed and were taken after manually setting the white balance of the camera to ensure consistent, accurate colour. The only significant difference is the background. The picture to the left was taken with the moth on a piece of bark while the picture to the right was taken with the moth on a piece of photographer’s grey card.

    While the picture to the left shows the moth in a natural setting and is the more aesthetic of the two, the picture to the right is superior when it comes to identification. The plain, neutral colour of the background makes it much easier to assess the wing shape and emphasises the colour of the moth.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (9)

    A further advantage of pure voucher photographs is that they can be combined into plates for comparison purposes. As an example, the picture below illustrates the variation in Clouded Drab (Orthosia incerta) from North Aberdeenshire (VC 93). Using software, the brightness of each image was slightly adjusted so that the grey background was exactly the same shade in each case and then resized to ensure a common scale. The modified images were then assembled on a grey background and labelled. The end result is an accurate representation of each moth illustrated with consistent brightness, colour and scale.

    Location The ideal place for photographing moths is an enclosed, well-lit space protected from the elements. This serves three primary functions by providing:

    • Good all-round lighting. • Shelter, to prevent movement from the wind and to keep you and the camera warm and dry. • An enclosed space, which allows you to retrieve moths when they inevitably make a bid for

    freedom.

    Unless you are in the field and are deliberately photographing moths in their natural environment, outdoor photography is not advised. Even the slightest of breezes can cause movement and blur the photograph. In practice you will have to use relatively fast shutter speeds with a wider aperture and as a result will have a much-reduced depth of field. In addition if (when!) the moth decides to make a break for freedom it will undoubtedly do so while you are concentrating on the camera monitor and unless you have a vigilant assistant on hand with a net, you will almost certainly lose it. It is far better to transport the moth and some suitable ‘props’ into a controlled environment for photography. The moth should, of course, be returned to the place of capture after photography.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (10)

    The photograph of the day-flying Common Heath to the left was taken by transporting both the moth and a few sprigs of heather to the ‘studio’ where I do most of my photography.

    ‘Studio’ is a grand term for what is in fact nothing more than the inside of a garden polytunnel. This is large (14’ x 21’), polythene covered greenhouse that provides a sheltered environment and good all-round illumination with the daylight gently diffused by the polythene cover. I use a wooden box as a working platform, with a second box as a seat. The camera is mounted on a mini tripod.

    From late summer to early autumn I avoid photography in the middle of the day unless the outside conditions are particularly cool and dull. On bright, sunny days the lighting is harsh and the warm conditions tend to make the moths active and difficult to deal with. Early morning and late afternoon or evening are best: the light is still good but the cooler conditions tend to make the moths more docile and co-operative.

    Any other enclosed structure that is well lit from several sides such as a porch or conservatory should serve equally well. Photography is also possible indoors next to a lit window, but unless you have a bay window you will probably need to use reflectors to overcome the highly directional nature of the lighting.

    Photographer’s Grey Card Photographer’s grey card (sometimes referred to as 18% grey card) is specially manufactured grey card designed to represent a scene of neutral grey colour and average brightness. It is an invaluable aid for macro photography that allows you to manually set the white balance for consistent, reliable colour. It can also be used as an aid to determining exposure and I often use it as a background for ‘pure’ voucher photography.

    Photographers grey card should be available from any good photographic store. I get mine from Jessops. As the size of the sheet (8” x 10”) is far too large for macro photography, I cut it into 4 smaller portions. This also allows the pieces to fit within my camera bag, although I always protect it by keeping it in a plastic bag. At somewhere in the region of £6 per sheet it is not exactly cheap, but the results make it well worthwhile.

    Camera Support Whether you are working under controlled conditions or in the field, some form of support for the camera is essential. Unfortunately, no single piece of equipment copes with a variety of different heights and as a result I have accumulated a number of different supports.

    Common Heath (Ematurga atomaria atomaria) f7.8, 1/8s

    The ‘studio’ in the polytunnel

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (11)

    Table-top Tripods These very small tripods come in a variety of styles with a simple ball head mount and either rigid or flexible legs. Their lightweight construction makes them very portable, but they are relatively unstable and prone to fall over when the camera is angled to take photographs with the moth on a flat surface. The models with flexible legs can be useful for taking photographs very low down in the field provided that you use two hands, one to grip the tripod and

    the other to operate the camera controls. They are cheap and useful items to keep in a bag or pocket for use in the field, but I would not recommend them for everyday use.

    Bean Bags Bean bag supports consist of a tripod screw mounted onto a tough, waterproof bag filled with plastic beans. They allow the use of the camera at very low levels and provide a good, flexible support platform. However, they are not very good if you want to point the camera vertically down. I usually carry one for use in the field and often use it for photographing moths and particularly larvae on low vegetation.

    ‘Mini’ Tripods In my opinion mini tripods are the best all-round support and they are my favourite piece of kit. I use a Velbon CX Mini tripod for most of my moth photography. This is a smaller version of a normal tripod that is only 30cm high when folded but can extend to 64cm. It can be used on a table top or placed next to a box, but is stable enough to angle the camera for photographing moths that are on a flat surface. It is also small enough to go in a decent sized camera bag or rucksack. The CX Mini is widely available and costs approximately £20. Jessops also produce a slightly cheaper ‘own-brand’ model with a similar size and specification (Jessops Tripod 318 Mini).

    Full Size Tripods Although I own a full-size tripod, I must confess that I hardly ever use it for photographing moths. It is simply too large to get close enough to the subject without the legs getting in the way. There is a possible argument for using full size tripods in some circumstances in the field, but I find that they are cumbersome and that the legs are prone to get tangled up in vegetation. By the time that I have adjusted everything and have got the camera into place the moth has usually gone – almost inevitably because my antics have disturbed it. Perhaps it is just me being clumsy!

    Table-top Tripods

    ”The Pod” bean bag support

    Velbon CX Mini

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (12)

    Monopods If I am photographing in the field and need some I height I use a monopod. These are much less cumbersome than conventional tripods but offer a less rigid support and consequently require faster shutter speeds. When I use one I invariably press the monopod against my leg to provide a more rigid platform. The main advantage of a monopod is that it can be moved into place quickly and much less obtrusively than a tripod. Monopods are more portable than tripods and some of the more expensive models can also double-up as a walking stick.

    Positioning Moths For most moths, the shape and pattern of the forewings are the primary diagnostic features and for voucher photography positioning the moth so that the forewings are in the plane of the photograph is the best choice. For moths that hold themselves more or less flat, a simple dorsal view will therefore suffice. This includes many of the noctuids and most of the geometers.

    Ingrailed Clay (Diarsia mendica)

    Riband Wave (Idaea aversata f. remutata)

    The way in which a moth naturally holds its wings at rest is important and this should always be taken into account. Moths that hold their wings in a ‘tent–shape’, e.g. Lesser Swallow Prominent, are usually best photographed from a lateral viewpoint and this may be the only viable option for geometers such as Bordered White that naturally hold their wings together in butterfly fashion. Some moths with a more three-dimensional aspect, such as Poplar Hawkmoth, are particularly awkward to illustrate using a single photograph. In such cases the best approach is to photograph the moth from a series of angles so that the combination of images provides a good overall impression of the moth.

    Lesser Swallow Prominent (Pheosia gnoma)

    Bordered White (Bupalus piniaria)

    A monopod

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (13)

    Poplar Hawkmoth (Laothoe populi)

    While most moths can be adequately photographed using common sense, some have diagnostic features that are not normally visible from a simple dorsal or lateral view. These require a little more thought and effort. Dark Marbled Carpet is a case in point. This is a variable moth that is similar to the equally variable Common Marbled Carpet. Distinguishing the two using the forewing is very difficult, but the sharp, acute angle on the central cross line of the hindwing of Dark Marbled Carpet is diagnostic.

    Dark Marbled Carpet (Chloroclysta citrata citrata)

    The moth in the above centre picture co-operated during photography by folding its wings together so that I could get a shot of the hindwings. The one to the right would not and so I simply took a photograph of it while it was in a transparent pot. It may not be an aesthetic photograph, but it does the job in voucher terms by capturing the diagnostic feature of the moth.

    Persuading Moths to Co-operate This is the tricky bit! Actually it’s not so bad, provided that you are sympathetic to the natural behaviour of the moth and, above all, patient. If you rush or try to manipulate a moth that simply doesn’t want to co-operate you are doomed to failure. The best results are almost inevitably obtained in cool conditions - as it becomes warmer, so moths become more active. In the summer I do most of my photography in the morning or early evening and avoid the heat of the day.

    For a voucher photograph, the best approach is usually to photograph the moth in its natural resting position. Most moths, particularly those that are nocturnal, will readily adopt this position provided that you give them a suitable substrate and keep them shaded until you are ready to take the photograph. Once the moth has settled down, leave it for a few minutes before attempting to photograph it. A moth that has been resting for a while is much less likely to react to changes such as exposing it to full light than one that has just settled down.

    Start with a docile moth in a clear container. If the moth is active to start with you will not succeed, so put the container in a cool, dark place and leave it for half an hour or so to allow the moth to settle down. I put the container under a piece of upturned plastic guttering, outdoors under a thick hedge so that it is kept cool and in deep shade. Some people like to use the fridge to cool moths down, but I find

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (14)

    that this rarely works for me. Yes, the moth settles down fairly rapidly, but I find that the rapid temperature rise produced by taking it out of the fridge into a warmer environment usually wakes it up and it quickly becomes active. I must admit, however, that the polytunnel where I do my photography is about 100 yards from the kitchen and the time taken to transport the moth coupled with some inevitable shaking does not help. Another reason for not using the fridge is that moth’s eyes adapt to the light and appear very dark when the moth is removed from the fridge. By all means try the fridge and see if it works for you.

    Transferring a moth from the container to the position required for photography is largely trial and error coupled with a healthy dose of common sense. The trick is to provide the moth with an opportunity to adopt a natural resting position of its own accord. Bear in mind that not all moths will react the same way. Some will settle quite happily on a relatively flat surface such as a leaf, a piece of bark or a stone, but others will prefer to cling to vegetation. Providing a surface that is similar to one that might be used naturally in the wild offers the greatest chance of success.

    When the moth is docile, place the container upside down over the surface where you want to photograph the moth. If you are very lucky the moth will crawl down onto the surface and settle down. If, as is far more likely, the moth remains clinging to the top of the container, a sharp tap on the outside can be used to dislodge it so that it falls onto the desired surface. Many moths, especially noctuids, seem to accept this and settle down again.

    Sometimes, however, the moth will persist in crawling back up the side of the pot. Try again; making sure that the container is shaded. Some moths seem to prefer moving towards the light and shading the container can reduce this tendency. If this does not work, try turning the inclination of the moth to crawl upwards to your advantage. Invert the container so that the moth is now on the base and the surface is at the top. Disturb the moth again and let it crawl back up until it is on the surface. Leave it for a while until it is resting quietly and then gently invert the container. With a little luck the moth will remain docile and you will be able to remove the container and photograph it. However, if all of this disturbance has made the moth active, you will have no alternative but to return it to a cool shady spot and leave it to settle down before trying again or using an alternative technique.

    I have had some success with particularly awkward moths by lining all of the surfaces of the container, including the lid, with bark or leaves and leaving the moth in the cool to settle down. With a bit of luck and a following wind the moth settles down and can then be photographed while it is still in the container. Sometimes, however, the moth insists on jamming itself into a corner of the pot and needs persuading to move.

    It is sometimes necessary to manipulate moths. Bear in mind that physically moving moths is likely to produce an alarm response and make them active. If you can, take a photograph first so that you have a voucher shot ‘in the bank’ before you try to reposition the moth. Try gently blowing on the moth - this rarely causes panic, presumably because moths are naturally subject to the wind, and the moth will often shift and settle down immediately. Blowing can also sometimes be used to persuade alert geometers with their wings folded to settle down and lay their wings flat – a position that presumably offers less chance of them being blown away. If you need to move a moth, try encouraging it gently with something soft but firm such as a grass stalk. Avoid making contact with the head area and especially the antennae, as this will provoke a more marked reaction from the moth.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (15)

    Deliberately irritating a moth is also sometimes worthwhile in order to get a better photograph. Many noctuids ‘play dead’ and while this makes it easy to obtain a voucher shot, it also makes for a very dull and lifeless photograph. Gently teasing them so that they extend their legs and antennae can make a major improvement. It can also persuade them to expose part of the hindwings, which for some species can be a diagnostic feature. One of the characteristics of Flounced Rustic (left) that helps to distinguish it from similar moths is the very pale hindwings.

    Some moths are more prone to take flight during photography than others. Noctuids and other relatively heavy set moths are generally the most docile (although there are exceptions, such as Large Yellow Underwing) and usually give advance warning of impending flight by vibrating their wings. Geometers are less predictable, although some that naturally hold themselves flat may raise their wings butterfly fashion as they become active but before taking flight. Most micros are particularly awkward and are prone to launching themselves into the air with no warning whatsoever. It is best to keep some form of cover, such as an inverted transparent pot, over the top of moth to prevent escape while you are composing the photograph. By all means keep a net near at hand just in case, but I have found that when a moth takes flight the best technique is to keep your eye on the moth and watch it carefully until it comes to rest. If you take your eye off the moth to reach for the net it is all too easy to lose sight of the moth. And keep the door closed: on more than one occasion I have forgotten and watched a departing moth fly unerringly through the door of my polytunnel and out into the garden!

    Documentation It is essential to keep proper notes and to properly document the photographs that you take so that you always know the size, location and date of capture of the moth. Without this information the photographs are useless as records. The camera itself will record the date and time that the photograph was taken, but this is not necessarily the same date that the moth was captured.

    It does not really matter how you record these essential details or how sophisticated your record system is as long as you do it and store the information in a way that makes it easy to retrieve. I make notes as I am taking the photographs and cross-reference the image name with the details of the moth. I use the same notebook that I use for all of my moth data. A typical entry is illustrated below.

    I record the date the photographs were taken, the photograph reference numbers (i.e. file names), the scale or size of the moth, the species, the location and the date of capture. The least important of all of these is the species name! This can of course come later or be revised. It is the date, location and size information that is important.

    Flounced Rustic (Luperina testacea)

    10/7/04 Photographs: DSCN 9682 – 9686 (Scale = DSCN9685) Purple Clay, Cairncummer (NJ925428), MV 9 Jul 04 DSCN 9687 – 9690 (h-wtip 10mm) Flax Tortrix, Cairncummer (NJ925428), MV 9 Jul 04

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (16)

    I also transfer the information from my notebooks to an Excel spreadsheet on a regular basis so that it can easily be retrieved when I am working with the photos. The Start and End columns in the spreadsheet refer to the DSCN4 image identification numbers, and hence to the file name.

    Photo Date Found Date Start End Scale Subject Notes

    10-Jul-04 09-Jul-04 9682 9686 9685 Purple Clay Cairncummer, MV

    10-Jul-04 09-Jul-04 9687 9690 h-wtip 10mm Flax Tortrix (Cnephasia asseclana) Cairncummer, MV

    10-Jul-04 30-Jun-04 9696 9712 Currant Pug (E. assimilata) aedeagus Backwall of Fetterletter, as 9647-49

    11-Jul-04 09-Jul-04 9725 9734 h-wtip 22mm Common Wainscot (red form) Backwall of Fetterletter

    11-Jul-04 08-Jul-04 9735 9748 h-wtip 18mm Scalloped Hook-tip Backwall of Fetterletter

    11-Jul-04 08-Jul-04 9749 9755 9751 Green Pug Backwall of Fetterletter

    Using a spreadsheet means that I can sort the records in a number of ways, for example by Found Date or Subject in order to locate a particular record. If worst comes to worst I can always use the “Find” function in Excel to find the record that I want. If I have taken photographs of a specimen that has already been photographed, I simply cross-reference it in the ‘Notes’ column of the spreadsheet. The third row in the diagram above illustrates a situation where I have cross-referenced photographs of a dissection with previous photographs of the imago.

    Data can also be embedded within the image file itself using software such as Adobe Photoshop. This might seem like a good idea, and by all means do it if you wish, but do not rely upon it. Some software packages do not preserve the information if the file is subsequently modified and saved.

    When it comes to recording moth size, I use one of two techniques. The first is to place a ruler next to the moth, take a photograph with the ruler and moth both in view, and record the ID of the photograph as the scale reference (e.g. Scale = DSCN9685). The size of the moth can then be derived from the photograph. This is simply a case of measuring a dimension on the moth and comparing it with the scale5. This can be done with software, on a print or even with a ruler on the screen. The Purple Clay illustrated has a forewing of ~18mm.

    There are occasions when positioning a ruler in a photo is difficult or inappropriate, either because there is no convenient surface for the ruler or because to do so might disturb the moth. In such circumstances I simply make a note of some aspect of the actual size of the moth, e.g. head to wingtip = 10mm. This can then be used to derive other dimensions. I usually do this with the moth safely returned to a transparent pot. I have to confess that I am sometimes forced to use this technique because I have forgotten to take a photograph with a ruler in place!

    4 DSCN is the standard identifier used by Nikon for naming digital still image files: DSCN0001.jpg, DSCN0002.jpg etc. Other manufacturers used different identifiers.

    5 This is only valid for dimensions that can be measured in the plane of the photograph.

    Purple Clay (Diarsia brunnea)

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (17)

    Organising, Backing-up and Archiving Photographs Having invested much time and effort taking photographs it is only common sense that you should use a logical system to store them, back them up and archive them. Once again, there are many techniques that can be applied so I will simply describe the system that I use and why.

    Organisation On my hard drive I have created a folder for my digital photographs. As I have recently upgraded from a Nikon Coolpix 990 to a Nikon Coolpix 4500 and want to keep the photographs separate, I have also created separate sub-folders for each camera. These are in turn subdivided into sub-folders named for the year and then the month. Folder names such as “09 Sep” rather than “Sep” are used so that when Windows lists the folders in alphabetical order they will also be in date order. Within each of the month folders I create a further subfolder called “Original”. This is where I download the images from the camera.

    I regard the images downloaded from the camera very much as digital ‘negatives’ to be preserved in their original form at all costs. When I process images, I never overwrite the original image in the “Original” folder and instead save the results into the higher-level month folder. In addition, any processed files that I save always carry the original file name and date so that they can be properly traced back into the documentation system. This becomes more and more important as time goes by and you amass more and more photographs. “Purple Clay.jpg” might sound like a perfectly reasonable file name at the time, but “DSCN9683 Jul 04 Purple Clay.jpg” is far better. It might be a bit of a mouthful, but the file name itself contains all the information needed to retrieve the original photograph and associated data.

    I also use a logical labelling system and include a discrete label on photographs when I print them. This consists of the image identifier followed by the month and year so that, for example, 9683/07/04 refers to photograph DSCN9683 that was taken in July 2004. This provides an immediate and obvious way of locating the both original photograph and the information about the moth.

    Out of habit, I download the photographs from the camera on a daily basis and only delete them from the memory card when I am sure that I have good, secure copies on my hard drive. This is purely safety-first: I have not yet lost any images from a memory card, but I am a pessimist at heart!

    Backing-Up and Archiving I regard backing up very much as a defence mechanism quite distinct from the task of archiving. For backing-up, I simply use a rewriteable CD to maintain a copy of the folder for the current month.

    Archiving is very different. Here the aim is to preserve the images on a long term basis in a form where they can be easily be located and retrieved when they are needed. At the end of each month I write the photographs for that month to CD-R. In the quieter parts of the year, when I am taking fewer photographs, I may extend this to every two months. I always create two copies of each CD: one for storage within the house and one for storage elsewhere. In addition to archiving the original and processed images, I also use the Web Photo Gallery facility available in Adobe Photoshop (and Photoshop Elements) to create a browsable index interface within the CD.

    The longevity of CD archives is open to debate and there has been much discussion on the web and elsewhere about the durability of the media, the file formats used and the software required to read

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (18)

    them. Some of this is justified and some is plain scare mongering. I believe that file formats such as jpeg are here for a long time to come and, while they exist, so too will the software required to read them. When they do eventually give way to other formats then there will be a lengthy and very obvious period of transition when action can be taken. Nothing lasts forever in either the analog or digital worlds. I have some 35mm slides taken in the late 1970’s, which, although stored properly, are now beginning to degrade significantly.

    A degree of common sense is therefore required. With an appropriate defence mechanism I believe that digitally stored images have the potential to outlive most other media provided that certain steps are taken.

    • Use only high quality, individually packed and reputably branded CDs (CD-R). Avoid rewritable CDs (CD-RW) and DVD. Rewriteable CDs are less stable and DVD is still relatively unproven as far as longevity is concerned.

    • When you record to CD, make sure that you finalise the disc and check that it reads correctly after you have created it.

    • Always create more than one copy of each CD and store them in separate locations. • Make sure that the images are in a commonly used, recognised format such as jpeg. • Save the image documentation on the same CD as the images themselves. • Store the CDs in appropriate, dust free containers away from the light. • Periodically check the CDs. If you find a problem don’t panic. The duplicate CD may well be

    OK and the data may still be retrievable.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (19)

    Using the Camera Throughout this document the term “Coolpix 4500 series” is used to describe the Nikon Coolpix 990, 995 and 4500 cameras. Where reference is made to a single camera model this is given in full, e.g. “Nikon Coolpix 4500”.

    Before you start, take time to read your camera manual and familiarise yourself with the controls. When you are actually photographing moths the last thing that you want to be doing is fiddling with buttons and trying to remember how to do something.

    Take Control of the Camera The Coolpix 4500 series are automatic digital compact cameras and although they have a high degree of manual override capability, many of the default settings are ‘auto’. In most cases these work well and produce reasonable photographs. However, if you want to take voucher photographs that can be directly compared with one another it is important that the same camera settings are used in each case. This cannot always be achieved if the camera is responsible for deciding what settings should be used for the simple reason that the camera may use one setting on one occasion and another setting on another occasion. To take effective, consistent photographs you should always be in control and aware of what the camera is doing.

    The most important things that you should manually override if possible are listed below. The terminology that I have used follows that used in the user guide for the Nikon Coolpix 4500. If you are using a different camera, consult your camera manual for the equivalent functions.

    White Balance. This controls the camera’s response to colour and should be manually calibrated against white or grey card each for each photography session. Manually setting the white balance promotes colour consistency and avoids colour casts. See Consistent Colour, page 29.

    Metering. This controls which area of the scene the camera will use to determine the correct exposure. Because moths can be both dark and light, assessing the exposure from the moth itself via spot or centre-weighted metering is usually inappropriate. The Matrix option, which assesses the whole scene, is preferred. See Metering, page 34.

    Best Shot Selector. When this is selected the camera will take a series of photographs6 while the shutter release button is held down and save only the sharpest. While this can be useful in certain situations, it is not appropriate for most voucher photography. See BSS, page 26.

    Image Adjustment. This controls the brightness and contrast of the photograph. To ensure consistent, comparable results it should be set to Normal. The Auto setting should be avoided as you will not know when and how the camera is adjusting the image.

    Saturation Control. This controls the saturation, or intensity, of the colours in the photograph. To ensure consistent, comparable results this should be set to Normal.

    Image Quality. Image Quality actually refers to file format. The Hi option saves the image data as an uncompressed TIFF file. This produces an extremely large file in excess of 11Mb that takes between 25 and 30 seconds to save and means that only a few images can be saved on even the largest capacity memory cards. The Fine, Normal and Basic options all save the image as a JPEG file. JPEG uses what is

    6 Up to a maximum of 5 on the Coolpix 4500 series cameras.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (20)

    called “lossy” compression, meaning that there is a trade off between image quality and file size. Higher quality images produce large files and lower quality images produce smaller files. JPEG files produced with the Fine setting are ~1.3Mb whereas those produced with the Normal and Basic settings are ~900Kb and ~500Kb respectively (the actual figures depend on how complex the image is). All are saved to the memory card in approximately 1 second. Images produced with the Fine option are actually of very high quality and virtually indistinguishable from TIFF images. Normal images are acceptable under some circumstances, but Basic images do show a significant reduction in image quality. I use Fine setting as standard but am prepared to use Normal if I am in the field and in danger of running out of space on the memory card. I strongly advise you to avoid both the Hi and Basic settings. If you are using a different camera I suggest that you take a series of photographs with each option and examine the results to see which is best for you. 7

    Image Size. There is little point in using anything but the largest image size available. On the Nikon Coolpix 4500 this is 2272 x 1704 pixels. The argument that you should use smaller sizes if you only want to produce small prints or e-mail the results does not hold water and it is far better to reduce the size using software after you have taken the photograph. I similarly see no advantage in the 3:2 aspect ratio that emulates 35mm format, as taking the image with the standard aspect ratio of 4:3 and cropping the photograph afterwards can better achieve this.

    Image Sharpening. This is a potentially controversial topic. Sharpening enhances contrast at the boundaries between light and dark areas to improve the clarity of the photograph. Some photographers like to set this to a low level and perform any image sharpening using software after the photograph has been taken. I have found that the Coolpix 4500 series cameras actually do a better job than software, possibly because the sharpening algorithm is applied early in the internal processing sequence. As a result I favour the Normal setting. Once again, Auto should be avoided for the simple reason that you will not know what the camera is doing and this may vary from shot to shot.

    Exposure Options. For normal operation AE Lock should be off and the exposure compensation (Exp +/-) set to 0. AE Lock can be useful in some circumstances for advanced exposure control and although exposure compensation is often necessary it is best set with the buttons on the camera rather than fiddling with the menu. See Exposure Compensation and Advanced Exposure Control, page 34.

    ISO. This controls the camera’s sensitivity to light and should normally be set to ISO 100, although in some circumstances an ISO value of 200 or even 400 may be advantageous. Avoid the Auto setting as this means that the camera will decide which ISO value to use. See Sensitivity (ISO), page 33.

    Focus Options. These options control what area of the scene the camera focuses on and whether it focuses continuously or only when you half-press or press the shutter. I strongly recommend that you use Manual AF Area mode as in the Coolpix 4500 series this allows you to choose one of 5 areas of the scene to be used as the focus point. I prefer Single AF as auto-focus mode and would also suggest that you turn focus confirmation on. See Focusing, page 23.

    Zoom Options. Digital zoom (as opposed to optical zoom) is a waste of time. It does nothing that cannot be done with the simplest of software and certainly does not capture any more detail. The Fixed

    7 Some modern digital cameras now offer the option to save images in “Raw” format. This is essentially a file that contains the unmodified image data captured by the camera together with the camera settings that were used at the time. Software supplied by the camera manufacturer can then be used to change some of the camera settings after the event. The Coolpix 4500 series cameras do not support “Raw” format, but if you have a camera that does this option should be investigated (paying particular attention to the file size and the length of time it takes the camera to store the image).

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (21)

    Aperture option is best turned on. This forces the aperture to remain the same (if possible) when you zoom the lens and this can be important in certain exposure situations. See Advanced Exposure Control, page 36.

    The settings that I most commonly use on the Nikon Coolpix 4500 shooting menu are listed below. I must stress that this list is only a guide and that some settings will need to be changed according to circumstance. With photography it simply is not possible to provide a series of settings that apply equally well in all situations. More detailed advice is provided in the sections that follow.

    Nikon Coolpix 4500 Feature/Setting White Balance White Bal Preset Metering Matrix Continuous Single Best Shot Selector Off Image Adjustment Normal Saturation Control Normal Image Quality Fine Image Size 2272 x 1704 User Setting 1 Image Sharpening Normal Lens Normal Exposure Options AE Lock Off Exp +/- 0 Focus Options AF Area Mode Manual Auto-Focus Mode Single AF Focus Confirmation On Zoom Options Digital Tele Off Startup Position Wide Fixed Aperture On Speedlight Options Pop-Up Auto Variable Power 0 Speedlight Cntrl Int&Ext Active Auto Bracketing Off WB Bracketing Off Noise Reduction Off

    Macro Mode In order to take close-up photographs of moths with a digital compact camera it is essential to use the macro close-up focus mode provided by the camera. For the Coolpix 4500 series this allows the camera to focus as close as 2cm from the subject. To place the camera into macro mode, press the focus button until the flower icon appears in the monitor.

    When you are in macro close-up mode you will find that focusing at the minimum possible distance from the subject is only possible in the middle part of the zoom range. The flower icon in the monitor turns yellow when the camera is optimally zoomed for close-up photography.

    There is a common myth that the Coolpix 4500 series cameras can only be used for macro photography at the ‘sweet spot’ in the zoom range when the flower icon is yellow. This is only true when the subject is at the minimum focusing distance of 2cm from the lens. As the working distance from the subject increases you will find that the possible zoom range also increases. As a general rule of thumb, if the camera can lock the focus onto the subject when you half-press the shutter release, then macro photography is possible.

    For all macro photography with the Coolpix 4500 series it is essential to use the monitor rather than the viewfinder to compose the photograph. This is because the viewfinder is offset from the lens and when

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (22)

    the subject is close the viewfinder will display a scene that is offset from the photograph that will be taken. The monitor displays the scene as it is seen through the lens.

    Reviewing Photographs You should always review the photographs that you take in the camera’s playback mode to check that all is well8. Make sure that you zoom in to the maximum level to check that the details are clear and the moth is in focus: a shot may look perfectly OK when the whole image is visible in the monitor but out of focus when you zoom in9.

    Be aware that the brightness of the image that you see in the monitor may be misleading and that many cameras, the Coolpix 4500 series included, automatically increase the brightness of the display for dark images. Assessing exposure using the monitor alone is therefore not advised and you should use always the histogram function.

    The Histogram Most higher-specification digital cameras, including the Coolpix 4500 series, include a histogram function that allows you to accurately and objectively assess exposure.

    The histogram takes the form of a graph similar to those illustrated to the left. The horizontal scale represents the brightness of the picture with black at the left and white at the right. The left part of the graph represents the shadows, the middle part represents the midtones and the right part represents the highlights.

    The height of the graph at any point illustrates the relative number of pixels in the image at that brightness level. This provides you with an objective, numerical way of assessing the picture.

    Diagram (a) shows a typical histogram from a correctly exposed image. The majority of pixels lie within the central portion of the graph, indicating that the midtones are dominant. The shadow area shows a smooth downwards curve with very few pixels at the black point, indicating that the subtle detail in the shadows has been captured. The highlight area shows the same trend.

    Diagram (b) represents an over-exposed image. The histogram is strongly biased towards the highlight area and is clearly ‘clipped’ at the right hand edge. This means that there are many pixels with the maximum possible brightness level (pure white) and that some details in the highlights will have been

    8 The mechanism for reviewing photographs after you have taken them varies from camera to camera and is different on different models in the Coolpix 4500 series. Check the user guide for details.

    9 The Nikon Coolpix 990 allows you to zoom in to a maximum of 4x when reviewing pictures but this was increased to 6x in the 4500.

    (a)

    (b)

    (c)

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (23)

    lost in ‘blown out’ areas. There are also very few pixels in the shadow area. This photograph should be taken again with a negative exposure compensation so that less light is allowed into the camera.

    Diagram (c) represents an under-exposed image. This has the opposite bias to an over exposed image with clipped shadows and few pixels in the highlight area. This photograph should be taken again with a positive compensation to allow more light into the camera.

    Many cameras also help you by indicating overexposure with blinking areas in the image preview. These areas have brightness values at the maximum level where no highlight detail will be discernible. However, you should not worry unduly if there are low numbers of very small blinking areas as these may well represent reflected highlights that cannot be avoided.

    On rare occasions, particularly if you are shooting in full sunlight, you may see a histogram with both the highlights and shadows clipped. This indicates that the brightness range in the scene is too much for the camera to cope with and that the camera’s dynamic range has been exceeded. This can be overcome by using the camera settings to reduce the contrast.10

    The reverse is not true and it is perfectly possible to have a voucher photograph with a low contrast range.

    The ‘pure’ voucher photograph to the right has the vast majority of pixels concentrated in the midtones with only very few dark or light pixels. Note the dramatic peak in the centre of the third quadrant, which represents the grey background.

    Focusing Most modern digital cameras have an automatic focusing system and in general these work very well, provided that you follow some simple guidelines.

    The depth of field of any lens is distributed approximately 1/3 in front of the focus point and 2/3 behind it. This means that it is better to focus on a closer part of the moth rather than a farther part. Ideally you should focus on a point near to, but not at, the closest part of the moth. For a dorsal voucher shot of a noctuid moth in a natural resting position, a focus point partway down the slope of the forewings is generally suitable. This will distribute the depth of field so that the entire moth is in clear focus.

    Try to make sure that the eyes of the moth are in focus, even for voucher shots. The human eye tends

    to be drawn to the moth’s eyes in a photograph and if they are out of focus the photograph will look horrible. Note that this does not mean that you must focus directly on the eye – just that the eye should be well within the depth of field. If in doubt, select a focus point that is approximately the same distance

    10 The contrast controls can be found under “Image Adjustment” in the Nikon Coolpix 4500 shooting menu.

    The ‘ideal’ focus point for an overhead

    (dorsal) voucher shot of a noctuid

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (24)

    from the camera as the moth’s eye. If this is obscured, try to make sure that any hairs along the crest of the head and thorax are sharply focused.

    Your camera user guide or manual may tell you that in order to focus on an off-centre subject you should centre the subject in the frame, half-press the shutter to lock the focus and then move the camera to recompose the shot before taking the photograph. Don’t bother – this rarely works for close-up photography for the simple reason that moving the camera to recompose the photograph will almost certainly change the distance from camera to subject and hence the point of focus. With a depth of field measured in millimetres this can be disastrous.

    Some cameras offer a choice between continuous auto focus (where the camera continuously adjusts the focus as the camera is moved) and single auto focus (where the camera focuses only when you half press the shutter release). Both work, but I much prefer single auto focus. Continuous auto focus drains the batteries quickly and I find the continual whirring of the lens motor extremely irritating.

    If you are using one of the Coolpix 4500 series cameras you will find that they also have a Manual AF Area option. This allows you to select one of five focus areas (centre, left, right, top or bottom), with the selected area shown in the monitor. I strongly recommend that you use this option as a matter of course as it will help you to compose photographs with a focus point that is not at the centre of the frame. If your camera does not have an equivalent function you will be forced to place the focus point at the centre of the frame and, if necessary, crop the photograph later to achieve the desired composition.

    The Coolpix 4500 series cameras also offer a focus confirmation option. This artificially highlights areas of focus in the monitor by a slight increase in sharpness and contrast. This helps you to determine which areas of the photograph are in focus and should therefore be turned on. This affects only the way in which the scene is displayed in the monitor and does not affect the photograph in any way.

    Manual Focus The Coolpix 4500 series cameras all feature a Manual Focus mode. Unfortunately, this has a very limited capability and is almost totally useless for macro photography. It simply allows you to preset the focusing distance on the camera. This is not on a continuous scale, but stepped, and at close focusing distances there are no intermediate steps between 2cm, 3cm, 4cm etc. This is hardly useful when the depth of field is measured in millimetres! The only way that manual focus can be used in practice is to preset the focus distance and then move the camera until the desired part of the moth is in focus. This should work in theory, but in practice the detail on the monitor is not good enough to be able to judge the focusing with any confidence.

    If you are using a different camera that offers manual focus I strongly suggest that you experiment with it and decide for yourself whether and when manual focus produces better results than auto-focus.

    Using The Self-Timer The self-timer available on most digital compact cameras is a valuable aid to macro photography. Most do not accommodate a shutter release cable and at very slow shutter speeds pressing the shutter release

    Elephant Hawkmoth (Deilephila elpenor)

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (25)

    button can cause camera shake and the photograph to be blurred. Using the self-timer helps to prevent this by creating a significant delay that allows residual movement to die away11.

    Having said this, even without the self-timer there is a short, but significant, delay between pressing the shutter release button and the photograph being taken. Provided that the camera is sturdily mounted on a tripod and you are not too clumsy, this delay may be long enough to make using the self-timer unnecessary. Paradoxically, one of the advances in digital camera technology has been the reduction of the delay between pressing the shutter and the photograph being taken and this delay is longer on the Nikon Coolpix 990 than on the Nikon Coolpix 4500. I suggest that you experiment and make your own mind up about whether and when you need to use the self-timer.

    Awkward Focusing Situations In certain situations you may find that the camera’s automatic focusing system insists on locking onto high contrast background detail rather than on the moth itself. This is most likely to happen if the moth is isolated in the foreground against an otherwise ‘busy’ background. The problem will be worse if the moth is relatively small in the frame, or is moving.

    The pictures to the left were taken in the field with the butterflies clinging to a grass stalk in a breeze. It seemed that no matter what I did, the camera always locked the focus on the grass stalks in the background, producing the photograph at the left. Needless to say, this was very frustrating!

    The photograph on the right was taken by forcing the camera to focus on the butterflies using the method described below.

    The following technique can be used to encourage the camera to lock onto the intended subject rather than on the background.

    1. With the camera firmly supported, compose the photograph. 2. Switch the camera to self-timer mode. 3. Place a piece of photographer’s grey card behind the subject, but in front of the background,

    and move it gently up and down or side-to-side.

    4. While you are doing this, use your other hand to press the shutter release button. The camera will be unable to focus on the moving card and the auto focus mechanism will focus on the intended subject. Using grey card means that the exposure, which is set at the same time as the focus, will be correct.

    11 The default self-timer delay is 10 seconds on the Coolpix 4500 series cameras, but pressing the shutter release a second time reduces this to 3 seconds. Frustratingly, after the self-timer has been used the Coolpix 4500 series cameras return the camera to normal focus mode rather than macro mode. You must therefore manually reselect macro focus mode each time that you use the self-timer.

    Green-veined White (Pieris napi) mating. f4.9, 1/300s.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (26)

    5. Remove the card and allow the self-timer to count down and take the photograph. This delay allows any residual movement caused by the card touching elements in the background to die away.12

    If you do not have a piece of grey card, simply using your hand will also work. Most skin tones are close enough to average lightness for this not to adversely affect the exposure.

    Provided that the subject is still, disturbing and blurring the background will not matter. In fact the reverse may be true, as macro photographs often look better with a sharply defined subject isolated against a soft, out of focus background. Try taking a bunch of suitable foliage and gently waving it around behind the moth as the photograph is taken. The result is often a soft, but natural looking background.

    BSS (Best Shot Selector) The Coolpix 4500 series cameras all include a feature called BSS (Best Shot Selector). With this enabled, the camera will continue to take photographs as long as you hold the shutter release button down13. When you let go of the shutter release button, the camera examines the images in memory and selects the one with the greatest detail to save to the memory card. This will normally be the photograph with the sharpest focus. Other digital cameras offer similar systems – check your manual for details.

    In general, BSS is not necessary for voucher photography under controlled conditions. It can, however, be useful in the field when there is some degree of movement. This is especially true if there is a light but variable breeze. Using BSS can help you to capture those brief moments when the breeze dies down and movement is minimised.

    While BSS will correctly reject blurred photographs in favour of sharper photographs, you should bear in mind that this is all it can do. It cannot differentiate between a photograph where the foreground is in focus and one in which the background is in focus. In particular, you should be aware that BSS might save a sharp photograph if movement has caused the focus point to switch to an object close to or behind the moth, but not the moth itself. Always check the results and if there are any problems, try again.

    Overall, BSS is most useful in cases where photography is marginal. It is of no advantage under still conditions, nor will it be able to deal with situations where there is any significant movement of the subject. However, in intermediate conditions where there is some limited movement of the subject it can be a considerable help and is well worthwhile trying.

    Depth of Field One of the biggest problems faced when photographing moths is that the depth of field, by which we mean the zone of acceptable sharpness in front and behind the point of focus, is very narrow at close focusing distances. Maximising the depth of field, and thereby getting the whole of the moth in crisp

    12 Nikon Coolpix 990 users will find the technique a little more difficult because the 990 sets the focus and exposure at the end of the self-timer countdown rather than at the beginning. This leaves less time for you to move the grey card out of shot. Nevertheless, I have found that the delay between the camera setting the focus and operating the shutter is long enough to move the card sharply out of the way. You do, however, need to make sure that this does not move the foreground and blur the photograph.

    13 To a maximum of 5 on the Coolpix 4500 series.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (27)

    focus, is very important for voucher photography. Although the depth of field offered by digital compact cameras is superior to 35mm SLR, this does not mean that you should not employ whatever techniques are available to maximise the depth of field.

    The mathematics behind depth of field are complex and well beyond the scope of this article. Nevertheless, there are some fundamental facts that you should be aware of, namely:

    • Depth of field is greater for small apertures (larger f-numbers) than for large apertures (smaller f-numbers).

    • Depth of field is greater for short focal lengths (wide-angle) than for long focal lengths (telephoto). In other words, as you zoom in the depth of field decreases.

    • Depth of field increases as distance to the subject increases.

    Because depth of field is so important, these are worth examining in more detail. As we shall see, focal length (zoom) and distance to subject cancel each other out and aperture turns out to be by far the most important factor for controlling depth of field.

    Aperture Depth of field is greater with small apertures (larger f numbers) than for large apertures (smaller f numbers). This is a fundamental property of all lenses and is clearly demonstrated by the following sequence of pictures, all of which were taken with a Nikon Coolpix 4500 manually focused at the minimum possible focus distance.

    f10, 1/19s f6.5, 1/45s f3.6, 1/150s The photographs show a progressive decrease in depth of field from smaller apertures at the left to larger apertures at the right. The black and white pictures are enlarged details that have been processed with a ‘find edges’ filter in Adobe Photoshop to highlight the detail and emphasise the acceptable zone of sharpness. At f10.4 this zone is between 4mm and 5mm deep, at f6.5 it has been reduced to approximately 2mm but at f3.6 it is little more than 1mm. In 35mm terms, f10 on the Nikon Coolpix 4500 is equivalent to f48, f6.5 is equivalent to f31 and f3.6 is equivalent to f17.

    As a result, if you want to maximise the depth of field you should use the smallest possible aperture. The downside of this strategy is that small apertures require correspondingly slow shutter speeds and this increases the risk of blurring due to movement by the camera, the subject, or both. In

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (28)

    practice the only way to get around this is to make sure that the moth is stationary when the photograph is taken and to always use a tripod or alternative support for the camera.

    Focal Length and Distance to Subject Depth of field varies with focal length. For any given aperture, wide-angle lenses have a greater depth of field than telephoto lenses. With a zoom lens, this means that zooming out produces a larger depth of field and zooming in produces a smaller depth of field.

    Given the above it might be reasonable to assume that moths are best photographed with the lens at the wide-angle end of the zoom range in order to maximise the depth of field. However, depth of field is also a function of distance from the lens, increasing when the subject is further away and decreasing when the subject is closer. At the wide-angle end of the zoom range objects appear smaller in the photograph and at the telephoto end of the zoom range they are larger in the photograph. To make the subject the same size in the photograph, the camera must be closer to the subject at wide angle than it would be at the telephoto end of the zoom range. So although wide angle offers a greater depth of field, the depth of field is reduced by the need to have the camera closer to the subject. The combined effect of these two factors is demonstrated in the photographs below:

    Zoomed out (focal length 10.4mm) Zoomed in (focal length 19.1mm) The photographs above were taken so that the ‘6’ and ‘1’ buttons on the ruler are in focus and approximately the same size in each photograph. The photograph at the left was taken with the lens zoomed out and the camera close to the subject. The one to the right was taken with the lens zoomed in and the camera further from the subject. The difference in perspective is obvious.

    Looking at the black and white images it is clear that the depth of field is the same in each case. The potential advantage of using wide-angle has been cancelled out by the disadvantage of placing the camera closer to the subject. This means that for any given size of subject in the frame, it does not matter whether you zoom out and position the camera close to the subject or zoom in and position the camera further from the subject: the depth of field will be the same.

  • Voucher Photography Using Digital Compact Cameras. Chris Harlow, February 2005. Issue 1.0

    (29)

    This has important practical implications when it comes to photographing moths. Photography is much easier with the camera zoomed in rather than out because the greater working distance between the camera and the moth makes manipulation of the moth much easier. In addition, when the camera is further from the moth there is less chance that the camera itself will cast an unwanted shadow in the photograph.

    What does matter, of course, is the relative size of the moth within the photograph. If depth of field becomes critical you can increase it by reducing the size of the moth within the frame. This may be particularly important when you are photographing smaller moths. In practice you will find that resisting the temptation to fill the frame with the moth will produce better, clearer results.

    Consistent Colour (White Balance) Photographers who use conventional positive or negative colour film will be familiar with a system where the reaction of the film to colour is fixed. Diff