joy of digital photography

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Joy of digital photography

Biman Basu

E-mail: [email protected]

Ever since its invention more than 180 years ago photography as a means

of permanently recording images had changed little till digital photography

made its appearance in the late 1980s. Conventional photography involves

three basic components camera, film (or plate) and chemical processing.

You load the film in the camera, shoot, and after exposing the entire film

roll send it for processing to a studio or photo lab. Of course, you can also

process it yourself if you have a dark room. After processing you get either

a negative, from which prints can be made on photo paper, or

transparencies that can be projected on screen with a slide projector.

Making prints from film negative is also a wet process and involveschemicals. All this takes time and so, in conventional photography you have

no way of knowing how the shots have come till you get the prints or slides

in hand. If something had gone wrong you can only feel sorry and brood, for

it may not be possible to get the same shots again.

All that has changed now with the coming of the digital camera a marvel

of optics and solid state electronics that has revolutionised a profession and

changed the way people create and share photographs. With a digital

camera you can see the result almost instantly after you click the shutter. If

youre not satisfied you can take the same shot again, and since you dont

use any film nothing is wasted. Another advantage is that you dont have to

worry about finishing the entire roll of film 24 or 36 exposures before

sending it to a photo lab for processing; you can take a single or only a few

shots and print them immediately, ideal for making passport and visa

photos at home. Not only that, you can edit and enhance the quality of your

digital photographs on your computer. Remarkable improvements are

possible with even the worst exposed digital images. And remember, you

dont need messy chemicals or a dark room to process or print your photos;

you can do it at home with your computer and inkjet printer. Lastly, you can

share your photographs with any number of friends and relatives anywhere

in the world almost instantly, by e-mail. However, in general, digital

cameras cost more than film cameras. But its a one-time investment. You

dont have to spend anything more on film, processing and prints; so in the

long run it turns out cheaper than film photography. Lets see how digital

photography makes it possible.

The digital camera

Of course, for digital photography youd need a digital camera. Digitalcameras can be either single-lens reflex (SLR), or non-SLR. Digital cameras
mailto:[email protected]:[email protected]


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for amateurs are basically non-SLR type; many are quite compact and can

be carried in a pocket. They are usually low-priced. They have a fixed lens,

usually with 3x zoom, which cannot be changed. Digital SLRs, on the other

hand, are quite expensive and are used mainly by professionals. Like any

SLR, they have interchangeable lenses which make them highly versatilefor professional photography.

In appearance a digital camera looks almost like a film camera. Just like a

film camera, a digital camera also has a lens (usually a combination of

lenses) mounted in a barrel in the front that focusses light to create an

image of a scene. In fact, you may not be able to tell the difference

between a film and digital camera until you look at the back of the camera.

Unlike a film camera, where you have to open the back to load the film, a

digital camera back cannot be opened because you dont have to load any

film. Instead it has an LCD monitor on which the scene being photographedappears. The large LCD monitor also allows you to compose the photo

meticulously. Some digital cameras also have an electronic view finder

(EVF) in addition to the LCD monitor which can be used at eye-level like SLR

film cameras. All digital cameras come with a built-in flash.

The image sensor

In a digital camera the lens focusses the image not on a film but on a solid-

state semiconductor device known as an image sensor, which is capable

of storing light electronically. An image sensor is generally a charge-

coupled device (CCD). It records the image as a pattern of pixels the

smallest units of any image. Thus in a digital camera the film is replaced by

an electronic image sensor and the camera basically captures a scene and

converts it into pixel values of electric charge, which are further processed

electronically to produce the image. The processed images are finally

stored either in the internal memory of the camera or on a memory card

that is inserted into a slot on the side of the camera. Unlike film, which can

be used only once and a bad shot means wasted film, a memory card can

be used again and again after formatting.

Capturing the image

In a film camera when light falls on the film the coating of silver halides on

the film undergoes a chemical change, breaking up into fine particles of

silver that produces the image in black and white and shades of grey in the

developed film. The density of silver particles (blackness) on the developed

film depends on the intensity of light falling in a particular area. Colour films

use multilayer coatings of silver halides along with dyes that bring out the

image in colour after chemical processing.


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In digital camera, however, no chemical reaction is involved to produce the

image; it is done electronically. Here, as we have seen, the film is replaced

by an electronic image sensor. Image sensors are basically silicon chips

(like the ones you have in the CPU of you PC, mobile phones, and other

electronic gadgets). Whereas for a 35-mm film camera the size of the filmis fixed at 35 mm, in most digital cameras the size of the image sensor is

much smaller usually not much bigger than the size of your fingernail.

The surface of an image sensor is made up of millions of extremely tiny

photosensitive diodes, each of which captures a tiny fraction of the entire

image (called a picture element or pixel in short). You can think of the

image sensor as having a 2-D array of thousands or millions of tiny solar

cells, each of which transforms the light from one small portion of the

image into electrons. The amount of charge depends on the intensity of the

incident light. The more the light hitting a diode, the greater the charge itrecords. When you click the shutter the lens opens for a fraction of a

second, as in a film camera. However, here the varying intensity of light in

the scene being photographed is not recorded on a film as silver specks,

but on an image sensor as a pattern of high and low charge of the diodes,

which is later processed into the digital image.

While most digital cameras use CCD as the image sensor, another type of

image sensor is also used in some digital cameras. It is called

complementary metal oxide semiconductor (CMOS). Unlike a CCD sensor,

in which every pixels charge is transported across the chip to a single

output node for further processing, CMOS sensors use, in addition to diodes,

a set of microscopic transistors on each pixel that amplify, convert and

move the charge. Often CMOS sensors also have additional circuitry for

noise correction and digitalisation circuits. For this reason CMOS sensors

tend to be larger and till very recently were considered to be superior to

CCDs and were used mostly in digital single lens reflex (DSLR) cameras.

But today we know that each type has advantages and disadvantages. For

instance, since each pixel on a CMOS sensor has a number of transistorsaround it, the light sensitivity is reduced as only light falling on a diode is

recorded. On the other hand, CCD image sensors do not have this problem,

but they consume a lot more power almost 50 to 100 times more than

CMOS sensors. So while buying a digital camera you have to choose

between higher sensitivity and longer battery life.

Pixel number

You often see digital camera ads with figures like 6 megapixels or 10

megapixels. What does this megapixels mean? It is actually the number

of pixels in the image sensor, which is a measure of the resolution of a


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digital image produced by the camera. A figure such as 10 megapixels (10

MP) means that the image sensor of the camera is made up of 10 million

(million = mega) pixels. It is obvious that more the number of pixels higher

the resolution of the image will be. It is like the half-tone images you see in

printed newspapers and magazines. The larger the dots the coarser theimages look and finer and closer the dots sharper the images appear. So, a

higher value of megapixels simply means that the images can be enlarged

more without breaking up into individual pixels. For amateur photography,

a resolution of up to 10 MP is considered sufficient. Higher megapixel

images can be blown up to larger sizes, but they have the disadvantage of

making the image files very large, which take up a lot more memory space

on the memory card and computer hard disc.

Camera controls

Before handling any gadget it is always better to get familiar with itsworking. Fortunately, digital cameras are among the most user-friendly

electronic gadgets available today. Remember, a digital camera is a

sophisticated gadget that is entirely controlled electronically, but its entire

functioning is menu based which makes it easy for even beginners to

master the controls fast.

In most digital cameras almost everything is in the auto mode and you

have just to aim and shoot. Of course, you have a choice to set the ISO

speed from a menu. The camera automatically sets the most appropriate

combination of the shutter speed and aperture, depending on the intensity

of available light, and also does the focussing. The shutter speed in digital

cameras can range from 1/2000 second up to 15 seconds depending on the

model. For focussing, there is a provision of selecting between centre-zone

and multi-zone focussing in some models, which can bring a small area or

a wider area, respectively, into focus. There is also a fixed-focus landscape

mode which is set to infinity and is very convenient for shooting distant

objects and landscapes, especially through glass windows or partitions

where autofocus cameras often try to focus on the glass pane rather than

the distant scene, producing out-of-focus images. Most digital cameras also

come with a macro mode which is very convenient for taking fantastic

close-up shots of small objects such as flowers from a distance as close as

one centimetre.

In addition to the auto mode, some digital cameras also have provision for

manual control, which is a great boon for those who want to be innovative.

In such cameras there are P A S M modes. The P mode is like the auto

mode where the camera sets the shutter speed and aperture depending on

the available light and ISO speed. In A mode you can set the aperture also known as f-stop or f-number and camera sets the shutter speed. In


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the S mode you set the shutter speed and camera sets the aperture. In M

mode you can set both the aperture and shutter speed manually to have a

variety of combinations not available in the auto mode. Some models offer

a burst mode which allows you to take up to six shots in quick succession.

This mode is helpful when taking shots of a fast moving object; you canselect the best out of the lot.

Most digital cameras come with a zoom facility that changes the lens from

wide angle to telephoto mode. The most common is 3x zoom. Zooming in

effect allows you to change the focal length of the lens without changing

the lens. The focal length of the camera lens is changed by forward and

backward movement of the lens elements within the lens mount. In 3x

zoom, the effective focal length of the lens increases three times. As a

result, objects appear three times larger in the image. In other words, it

means that you can shoot a distant object as if it were three times closer toyou. If you use a 10x zoom youll be surprised with what you get fantastic

shots that you can never get with a normal lens. Digital cameras up to 20x

zoom are available which are ideal for shooting animals and birds in zoos

and distant mountain peaks and taking candid shots of people, especially

children.

A bonus that comes with a digital camera is the video option. On the press

of a button or turn of a knob your camera becomes a video camera. You

can shoot videos with sound of up to one hour duration. Although the

quality is not as good as taken with a video camera such as a Handycam,

videos taken with a digital camera are of reasonably good quality and you

can view them on your TV set or computer monitor.

Image stabilisation

An exciting development in digital photography in the past few years has

been the provision of image stabilisation, which addresses one of the

common causes of blurred photographs: camera shake. Most cameras now

come with image stabilisation, anti-shake or vibration-reduction features to

counteract camera shake, which can ruin an otherwise good shot.

A photograph, whether it is recorded digitally or on film, is usually regarded

as a frozen instant in time; but this is not strictly true. It is no doubt a

record of a very short interval of time, but it is not instantaneous. The time

interval recorded is the shutter speed used to take the photo. In most cases

this is of the order of less than 1/100 second, which is quick enough to

freeze most movement.

Camera shake is most likely to be a problem when youre taking photos in

low-light conditions without a flash. If there isnt much light, your cameramay automatically switch to flash mode. But flash may not be desirable


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always, especially if you are taking a portrait in soft light or photographing

a baby. If you turn off the flash (which you can) the camera will

automatically set a slower shutter speed and higher ISO to compensate.

Higher ISO speed makes the picture grainy and a slower shutter speed

would mean that youll have to hold the camera still for longer, or use atripod. The problem is, when using a slower shutter speed, not only will any

movement of the subject be blurred, but also any movement of the hand-

held camera while the shutter is open will cause the entire picture to be

blurred. This is even more of a problem when using longer focal lengths,

such as with a zoom lens. The lens not only magnifies the subject, it also

magnifies any movement, exacerbating the effects of camera shake.

For taking blur-free photos, the rule of thumb is to use the reciprocal of the

lens focal length in mm as the shutter speed in seconds. For example, if the

focal length used is 100 mm then a shutter speed of 1/100 second or fasterwill prevent a blur. But 1/100 second wont be enough if the lens focal

length is set at 200 mm; then a minimum shutter speed of 1/200 second

would be needed. If you use a slower speed blurring of the image is likely.

But cameras with image stabilisation offer at least three stops of extra low-

speed stability. So, for example, a shot that would have needed a shutter

speed of 1/250 second to ensure shake-free results can instead be taken at

1/30 second with no problem. So, if you have a camera with image

stabilisation shoot away without worrying about camera shake even if your

hand is not rock steady!

Scene settings

In addition to landscape and macro settings, most digital cameras also

come with a scene mode which provide up to 20 options for shooting in

any situation. The options include landscape, close-up, sport, night portrait,

night landscape, candle light, snow, beach, fireworks, children, panning

shot, sunset and many others. For each mode there are camera pre-

settings that allow you take perfect pictures without worrying about the

aperture and shutter settings. Some digital cameras also have a

panorama setting for producing beautiful panoramas of scenic places from

multiple images.

Image storage

As we have already seen, digital cameras do not use film. Instead they use

a memory card to store the images. This is part of what makes digital

photography so exciting. Unlike film, the memory card is a one-time

purchase (one often comes with the camera). It can be used over and over

and a 1GB memory card can store more than five hundred pictures taken

with a 6MP camera. After you snap the pictures and transfer them to yourcomputer, the memory card is ready to be used for new photos. In addition,


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memory cards are more durable than film and they are not harmed by

airport X-ray scanners. There are about eight different types of memory

cards in use by different cameras, so make sure what type of memory card

your camera uses before buying one. It is always advisable to carry an

extra memory card when you are going on a vacation so that you never runshort of storage space for your images!

Image transfer

After you have taken the shots the next step would be to transfer the

images from the memory card to computer hard disc. Most digital cameras

come with software that has to be installed in the computer for

downloading and editing the images. But Windows XP can also download

images without any additional software. The camera is usually connected to

the computer through a USB cable, but you can also transfer the images

without connecting if both are Bluetooth enabled. Save the images in adesignated folder which you can access easily.

Once transferred to your desktop or laptop the images can be edited if

necessary to remove any error in exposure or blemishes. (Some cameras

provide in-camera editing facility also.) Although software supplied with

camera can be used for editing digital images, one of the most versatile

software for editing is Adobe Photoshop which allows a wide range of

manipulations including brightness, contrast and colour correction, image

sharpening, hue and saturation adjustment and many other options to

enhance or modify images.

The best part of digital photography is the ease with which the photos can

be stored and shared. No need to have bulky albums. No danger of the

photos getting discoloured with age. You can save them in your computer

hard disc and view them on your computer screen. You can also transfer

the images to CDs for safe storage and later viewing. You can send the

images to your friends or loved ones through e-mail without worrying about

loss or damage in transit. Of course, you can print some of them if you like

to have them framed for your drawing room or bedroom.

The world of digital photography is indeed full of opportunities. If you are

creative you can produce fantastic pictures with your digital camera with a

little effort. So have a digital camera, go and click away, and enjoy the thrill

of digital photography!

joy of digital photography

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