digital camera reviews - 10 things you need to know before buying a digital slr

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10 THINGS YOU NEED TO KNOW

BEFORE BUYING A DIGITAL SLR...

SLR advantages

The advantages of SLRs over compact cameras are many and varied — starting with the all-important image

sensor.

Many compact cameras may equal or eyen exceed some SLRs in their megapixel f count, but outright resolution

isn’t the primary concern. Image sensors in SLRs are physically larger than those in compact cameras, giving two

key bonuses. First,

Bigger sensors mean bigger pixels that i individually capture more light. This has the potential to massively

reduce digital image noise, which can give photos a grainy appearance, especially when shooting at higher ISO

settings. Second, larger sensors enable a smaller depth of field (the distance between the nearest and furthest

points in a scene that can I be kept sharp), enabling you to throw the j background out of focus and make the

main point of interest really stand out. This is especially useful in portraiture. Another critical benefit is that an

SLR enables you to literally look through the lens when composing shots. There’s no beating an optical

viewfinder that leads the eye right into the scene with perfect clarity and sharpness.

The perfect camera

Ergonomically, the larger build of an SLR makes for much more natural and comfortable handling, while manual

zoom and focusing rings on the lens enable far greater precision and control when composing and focusing.

Furthermore, buy an SLR or a compact system camera and you’re literally buying into a whole imaging system,

with the possibility of buying additional lenses and accessories that can turn your camera into the perfect tool

for any shooting scenario. Over the next few pages, we’ll take a detailed look at the principal differences

between different types of SLRs and CSCs (which feature interchangeable lenses, but have no reflex mirror) so

that you can make the best possible choice when picking out your new camera.


Traditional SLR design, new SLR features

1 Trad

ition

al SLR d

esign

, ne

w SLR

featu

res

Most digital SLRs look just like their film-based predecessors, but look a little closer

and the latest models offer a host of innovative refinements

Shooting modes

All SLRs tend to feature the conventional range of auto, program, aperture

priority, shutter priority and manual shooting modes, generally available from

a simple mode dial on the top of the camera. Those aimed at beginner and

intermediate users, such as the Canon EOS 550D and the Nikon D3100 also

include dedicated modes such as ‘scene modes’ on compact cameras, for

portraits, landscapes, sports and the like.

LCD screen

LCDs are not only important for accessing the camera’s menus, but are also

vital for I' reviewing shots to check exposure accuracy and sharpness. Budget

cameras such as the Canon EOS 1100D often have relatively 7 low-resolution

LCDs of about 230k pixels, whereas upmarket models such as the Canon EOS

60D deliver razor-sharp displays of 1,040k.

Reflex action

The main difference between SLRs and CSCs is that SLRs have a mirror

assembly that directs the image from the lens up into the optical: viewfinder,

enabling you to see the exact effects of focusing and zooming with absolute

clarity. The viewfinder itself tends to be more refined on upmarket model,

while the reflex operation of the mirror flipping up when you take a shot, so

the light can be redirected to the shutter and sensor behind it, is also usually

quieter.

Autofocus

Larger numbers of autofocus points enable you to select one that exactly

matches the critical point of focus in a shot, and multiple point s can track

erratically moving objects in continuous autofocus modes. Cheaper cameras

usually feature nine or 11 autofocus points, whereas more sophisticated

models often have more. The Nikon D300s provides no fewer than 51 points

ISO sensitivity

This is an aspect of SLRs that’s been considerably improved over the past few

years, with higher maximum ISO ratings enabling faster shutter speeds in low-

light shooting. Increasing the ISO makes the sensor more sensitive, allowing

your camera to take pictures in poor light without the need to use long shutter

speeds. The higher the ISO number used, the higher, the sensitivity; but the

greater the level of digital noise. Older designs, such as the Canon EOS 1000D,

usually offered a maximum of IS01600, whereas current models, such as the

Canon EOS 1100D provide a much higher sensitivity of around IS06400 in the

standard range, with expanded (lower image quality) options of up to

IS012800. Top pro models, such as the Nikon D3s, allow you to shoot at up to

IS0102400. Improved sensors coupled with smarter image processors bring

the possibility of high ISO settings with impressively low noise.

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CSCs - the new breed of cameras

2 C

SCs - th

e n

ew

bre

ed

of cam

eras

Halfway between compact cameras and SLRs, so- called compact system cameras

(CSCs) give you interchangeable lenses in a smaller, more portable package

Look, no mirrors

The main difference between a CSC and an SLR is that a CSC has no flip-up

mirror assembly or optical viewfinder — so although it has interchangeable

lenses, and sometimes an electronic viewfinder, it’s not technically an SLR. The

revolutionary design means fewer moving parts, and the possibility of smaller,

lighter designs. Yet another diversion comes in the shape of the Sony SLT

cameras, which have a fixed, translucent mirror that splits the light path

between the main image sensor and a separate phase-detection autofocus

sensor.

Viewfinder

Some CSCs rely on the main LCD screen for framing shots because there’s no

viewfinder. Models such as the Panasonic G3 have electronic viewfinders

(EVFs) built into the body, whereas others, such as the Olympus PEN E-P3,

include an optional EVP as part of the camera/lens kit. These EVFs are certainly

improving, but (apart from the one in Sony’s new NEX-7) they still lack the

sharpness of an SLR’s optical viewfinder.

Compact design

Offering significant downsizing from relatively chunky SLRs, a CSC such as the

Sony NEX-5N body measures just 110.8x58.8x38.2mm (WxHxD) and weighs

210g, compared with the (still relatively small) Sony A290 SLR (128x97x79.6mm

and 456g). Most models come with the option of a fixed focal length ‘pancake’

lens that, while not offering any zoom facilities, and continues the

miniaturization theme with ultra-compact dimensions.

Image sensor

The physical size of the image sensors are a match for their SLR counterparts,

with Olympus and Panasonic Micro Four Thirds cameras both using the same

dimensions as for sensors in Olympus Four Thirds SLRs (such as the E-30 and E-

5). Sony and Samsung sensors are larger, with a more regular APS-C-sized

sensor, similar to those fitted to all but pro-level full-frame SLRs. There’s

typically no shortage of resolution either, with pixel count ranging from around

12Mp to 16Mp in the latest models.

Interchangeable lenses

The key benefit of CSCs over compacts is that lenses are interchangeable.

Olympus PEN and Panasonic Lumix G series cameras are best sellers. They

share the Micro Four Thirds lens mount, while the Sony NEX cameras use

Sony’s proprietary features, such as autofocus, may not work.


It's not just about the camera body...

3 It's n

ot ju

st abo

ut th

e cam

era b

od

y... SLRs are often called ‘system cameras’, because the camera body itself acts as the

hub of an expandable system that includes lenses, flashguns, remote controls and

other accessories. It’s crucial to consider the quality and scope of a manufacturer’s

system as a whole, rather than getting hung up on features that are specific to just a

particular camera body

A lens for all reasons

From wide-angle and fisheye lenses to monster telephoto zooms that have

telescopic reach, the real versatility of SLRs stems from the fact you can swap

lenses in just a few seconds. It’s important, therefore, to look at the breadth of

lenses available when choosing which make of camera to buy, depending on

the type of photography you most enjoy. Canon and Nikon offer the widest

ranges of lenses, but keep an eye on prices, too, as these can vary wildly. For

example, a Nikon AF-S DX 10-24mm f/3.5- 4.5G ED will set you back £670,

whereas the closest Four Thirds equivalent, the Olympus ZUIKO DIGITAL ED 7-

14mm 1:4.0, costs around £1,550.

Third-party add-ons

You can often save money without sacrificing quality by going for third-party

lenses and other accessories. For lenses in particular, Sigma, Tamron and

Tokina all make good-quality alternatives to own-brand lenses. However, some

of their most I desirable newer lenses are only available in Canon or Nikon

mounts, so, again, it pays to check the availability of specific types of lenses

that you think you might want to add to your collection in the future.

Get flash

Most SLRs come with a built-in pop-up flash, but these are no substitute for a

proper flashgun, which offers much more power; Good flashguns also include

bounce and swivel heads for softening the quality of light by bouncing it off

ceilings or walls, as well as motorized heads, which can automatically increase

the flashgun’s reach when using longer focal length zoom settings. Dedicated

flashguns enable automatic flash zooming, along with accurate through-the-

lens (TTL) metering for correct exposures.

All SLR manufacturers offer their own flashguns, but as with lenses, good third-

party equivalents are often available at lower prices from the likes of Metz,

Nissin, Sigma and Sunpak.

Better connected

Some ‘system’ features extend from the camera in a particularly digital way.

For example, while there’s nothing new about sockets for plugging in a remote

control to avoid camera shake, extra connections include anything from USB

terminals for downloading your photos, to mic sockets for plugging in external

microphones, and HDMI sockets for viewing your photos on a high-definition

television.


Pixels: how many do you need?

4 P

ixels: h

ow

man

y do

you

ne

ed

? The megapixel count is often the first thing consumers consider when choosing a

new camera. But are massively high sensor resolutions really that important, and is

there a catch?

Des-res

How much resolution is desirable? The first consumer-level SLRs had sensors

capable of producing images of about 6Mp in size. This seems tiny by today’s

standards, but even this was plenty for producing excellent poster-sized prints.

The smallest pixel count you can expect from a current SLR is 12.1Mp, while

Canon, in particular, is pushing the boundaries with its intermediate- level

range, with all of its current line-up except the EOS HOOD and EOS-1D Mark IV

offering resolutions of at least 18Mp. As far as APS-C cameras go, Nikon is

playing catch-up, with its APS-C range offering pixel counts from 12.3Mp to

16.2Mp. Nikon’s full-frame D3x offers a whopping 24.5Mp, however, which is

bettered only by the Sony A850 and A900 (both 24.6Mp). By comparison, both

Canon’s current full-frame SLRs (the EOS 5D Mk II and EOS-Ds Mark III) offer

resolutions of 21.1Mp. Ultimately, 12Mp is plenty for most practical situations.

Creative cropping

Images with higher resolutions enable tighter cropping, so for example, if the

lens you’re using won’t give you enough telephoto reach, you can take your

shot anyway and cut out just the section you need. Even so, there are dangers

with this, as very tight cropping places much greater demands on lens quality,

because any lack in sharpness or the presence of chromatic aberration (color

fringing) will become more noticeable.

File sizes

Higher resolution images inevitably mean bigger file sizes, especially if you

shoot in raw mode to enable corrections to exposure, white balance and

picture style (color and contrast options) later on at the editing stage. For

example, a typical raw file from an EOS 550D or EOS 7D can be around 25Mb in

size, whereas the same image might only be about 10Mb from a Nikon D90 or

D300S. This not only means that your memory cards will fill up much quicker,

but also that the camera can slow down in a shorter space of time when

shooting in continuous drive mode, because you’ll have to wait for the

camera’s internal memory buffer to clear to the memory card.

Image noise

To squeeze more pixels onto a sensor that has the same physical dimensions,

each ‘photo site’ needs to be smaller, and can therefore capture less light. The

trade-off for higher resolutions is often an increase in digital image noise,

which gives pictures a grainy appearance, especially when shooting at medium

to high ISO settings. The latest sensor designs aim to minimize the gaps

between adjacent pixels, coupled with advanced in-camera image processing

to smooth out the noise.




Sensor sizes: which is best?

5 Se

nso

r sizes: w

hich

is be

st? CCD (Charge Coupled Device) sensors were used in many early SLRs, as well as some

current models such as the Sony A390, but CMOS (Complimentary j Metal Oxide

Semiconductor) sensors j are nowadays generally preferred.

Advantages include much lower power consumption, which extends camera battery

life, and the fact that CMOS chips can process as well as capture the image

APS-C

The vast majority of SLRs currently on the market use an APS-C-sized sensor,

approximately based on the size of a frame of APS (Advanced Photo System) film.

APS film cameras themselves were quite short lived, bridging the gap between

film photography and the advent of digital. A frame of APS film is somewhat

smaller than that of regular 35mm film, measuring about 25x17mm as opposed

to 36x24mm. APS-C digital sensor sizes vary slightly between manufacturers, with

Nikon, Pentax and Sony making sensors that have a 1.5x focal length conversion

factor (or crop factor), and Canon producing very slightly smaller sensors that

have a 1.6x conversion factor. APS-C sensors are much cheaper to make than full-

frame sensors (see below), making this type of SLR far more affordable. Another

advantage of APS-C sensors is that the conversion factor of 1.5x or 1.6x gives a

telephoto lens of, for example, 300mm a longer ‘effective focal length’ of 450mm

or 480mm respectively, therefore giving you more telephoto reach with

relatively small, lightweight and inexpensive lenses.

Four Thirds

Pioneered by Olympus, the Four Thirds format gives a slightly squarer image than

most SLRs, due to its 4:3 aspect ratio. ‘Designed for digital’, it’s more in keeping

with the aspect ratio of traditional compact cameras, televisions and computer

screens, but now that everybody’s gone widescreen it seems to have been a step

in the wrong direction. Four Thirds and Micro Four Thirds image sensors (the

latter used in CSCs), are larger than those of compact cameras, but smaller than

sensors in APS-C cameras. The result is a 2.0x focal length conversion factor,

which is great for extending the effective reach of telephoto lenses even further,

making Four Thirds a good choice for sports, action and wildlife photography.

The flip side is that it fails to produce such a shallow depth of field, making it

harder to isolate foreground objects by blurring the background. Increasing the

resolution of these smaller sensors without increasing digital image noise is also

more of a technical challenge.

Full Frame

As its name suggests, full-frame sensors are the same size as a full frame of

35mm film. There’s no focal length conversion factor to apply, so lenses act in

exactly the same way on this type of SLR as on a 35mm film camera. Pro

photographers, especially those involved in portraiture, i love them because they

offer a much shallower depth of field than APS-C or Four Thirds cameras at any

equivalent ‘effective’ focal length.


Lights, camera, action...

6 Ligh

ts, came

ra, action

... Until recently, the ability to capture video in what was primarily a stills camera was

the preserve of digital compact cameras. The advent of live view, which enables you

to compose shots using the camera’s LCD rather than the viewfinder, means that

more and more SLRs boast HD video-shooting capabilities

Evolution

The first SLRs to feature video capture were quite high-end affairs, such as the

Canon EOS 5D Mk II, but HD video has rapidly filtered down to more affordable

models such as the entry-level Nikon D3100 and Canon EOS 550D. Considering

its rich video-capture heritage, Sony was comparatively slow off the mark, but

models such as the A580 and SLT A55 brought the company up to speed.

HD formats

Video capture has, by and large, kept pace with popular consumer television

specifications, so cameras launched a year or two ago typically offered a

maximum high-definition resolution of 720p, dividing the screen image into 720

horizontal lines and using the progressive capture technology, which refreshes

the whole picture every frame. By comparison, 720i (interlaced) only refreshes

alternating lines with successive frames. The latest cameras typically offer Full

HD video recording, which is 1080p.

Frame rates

A range of frame rates, including 24,25,30 and 50fps (frames per second),

enables conformity to basic and high- end video production, television and film

standards around the world. This is becoming particularly important because

SLRs are increasingly being used to shoot professional video for TV adverts and

dramas, especially as the increased image sensor size of SLRs enables greater

blurring of the background, with a tighter depth of field for that filmic look.

Keep it sharp

One area that most SLRs struggle with is autofocus during video capture. The

Nikon D3100 leads the way here, being the first SLR to offer fast, constant

autofocus while shooting.



What Price Quality?

7 W

hat P

rice Q

uality?

It’s often hard to spot the difference between images captured on a £300 entry-

level SLR and a fully professional model costing upwards of £5,000, so you have to

wonder why there’s such a huge range in prices, despite the obvious sensor size and

resolution differences. The devil, as always, is in the detail

Material gain

It takes a tough camera to stand up to the rigours of daily professional use,

firing shots all day or night and quite literally getting bounced around from pillar

to post. Most budget cameras have a plastic shell, which is more than capable

of giving good service over many years of Careful use, but to take the bumps

and scrapes of heavy use, upmarket models such as the Canon EOS 7D, Nikon

D300S and their ilk generally have a tougher, magnesium alloy shell. Top-flight

professional cameras such as the Canon EOS Ds Mk III and Nikon D3x are even

more rugged — literal heavyweights in the field with battleship build quality

Whatever the weather

Most of us are rightly wary about getting our cameras out when it’s pouring

with rain — electronics and water never make a good mix. However, pro

photographers covering news, sports or even weddings don’t have the luxury of

waiting for the rain to stop, so pro-spec cameras usually feature extensive

weather-sealing around I all the buttons, switches, memory flaps and battery

compartments, along with any other joints that could ingest dust or water. This

makes production much more expensive, usually leading to a significant hike in

the purchase cost.

Built to last

Even the keenest amateurs might only average a few hundred shots each week,

but professional photographers can end up taking thousands of shots per day so

their kit has to be built to last. High-end and top-spec cameras are created with

this in mind, often having shutter mechanisms that are built to last for anything

from 150,000 to 300,000 shots.



You can see clearly now…

8 Y

ou

can se

e cle

arly no

w…

The viewfinder is your eye on the world, so the bigger, brighter and clearer its

image, the better. This helps not only for accurate composition, but also for greater

precision when adjusting focus settings

Pentamirror

Cheaper, entry-level SLRs such Its the Sony A390, and even some more

expensive models including the Canon EOS 550D and Nikon D5100, use

pentamirror viewfinders. These are cheaper to manufacture and lighter in

weight than ‘proper’ pentaprism viewfinders, being constructed from a set of

three separate mirrors. The main disadvantages of pentamirror-based SLRs are

that the images they produce are a bit dark and gloomy, and can be a little

lacking in contrast and outright sharpness. This doesn’t affect the recorded

image, just the image you see through the viewfinder.

Pentaprism

Based on time-honored tradition, the best viewfinders, as fitted to upmarket

cameras including the Canon EOS 60D and EOS 7D, and the Nikon D7000 and

D300S, as well as all full-frame cameras, - are of the pentaprism variety.

Constructed from a single, five-sided block of glass, the pentaprism reflects the

image directed up from the reflex mirror twice, so that it appears the right way

up and the right way around when viewed through the eyepiece. Pentaprism

viewfinders are relatively heavy and expensive to make, when compared with

pentamirror viewfinders, but produce better quality, brighter images.

Electronic

For CSCs that lack a built-in optical or electronic viewfinder, there’s often an

electronic device available as an optional extra, such as the Olympus EVE VF-3

viewfinder for the Olympus E-PL3.

Optional EVFs usually slot into the hotshoe at the top of the camera, but they

are typically expensive at about £150 to £200. Drawbacks are that you can’t use

the viewfinder and a flashgun at the same time, and that electronic viewfinders

lack the clarity of an optical viewfinder, being essentially mini-LCD screens.

Sluggish refresh rates also tend to give the viewed image a smeared appearance

when panning

Field of view

Ideally, it’s good to be able to see the whole of the image that you’ll capture in

the viewfinder, but in practice, this often isn’t the case. Many viewfinders,

especially cheaper pentamirror types, typically only give a 95 per cent field of

view, so you can’t quite see everything that will appear in the picture. In

practice, this isn’t too much of a problem, as it’s good to have a little Spare to

play with, because the edges of an image can be lost if you need to straighten it

(eg level the horizons) when editing. Good pentaprism viewfinders often creep

up to around 98 per cent coverage, and the best.... provide a full 100 per cent

view.

Magnification



Power with control

9 P

ow

er w

ith co

ntro

l Power, as they say, is nothing without control. That’s particularly true in advanced

digital photography, because while a camera can give you all the advanced features

under the sun, they’re not much use unless they’re also easily accessible under your

fingertips

On the button

For more advanced, creative photography, it’s vital to have quick access to

important imaging parameters such as metering mode, exposure compensation,

white balance, ISO, autofocus mode and drive mode. There’s nothing worse than

missing a priceless shot because you were too busy hunting through arcane

menu systems to find the setting you needed. Advanced SLRs generally make

more of these settings instantly available, with dedicated buttons on the top and

back of the camera.

Information overload?

There’s a lot of information that’s worth keeping tabs on while you’re shooting,

including aperture, shutter speed, exposure compensation and autofocus

confirmation, at the very least. All SLRs should give a constant supply of these,

right in the viewfinder where you need it most. The majorities of current

cameras usually give the option of viewing wider-ranging information on the

main LCD at the back of the camera; while more advanced models generally have

a supplementary black-and-white mini- LCD on the top plate, so you can always

see exactly what’s going on, even when shooting with a tripod.

Perfect fit

The size and shape of a camera body is surprisingly important. If you’ve got big

hands, a small lightweight SLR with a tiny hand grip simply won’t feel natural,

and apart from being awkward to use, your shots will be more prone to camera

shake. It’s well worth trying a few different bodies in a camera shop to get a feel

for them before buying.

Quick control

A little help can go a long way, and cameras increasingly have on-screen help

systems to guide you through their features and functions. A pared-down

shooting menu is also often delivered on the main LCD, enabling quick access to

important shooting parameters while keeping button layouts simple and

uncluttered.

As you like it

Fussy photographers like to set up cameras to the nth degree, so that all the

finer points, such as the size of the ‘center’ in center-weighted metering, is

exactly as they want it. As a rule, Canon, Olympus and Pentax cameras offer a

reasonable amount of customization, Sony less so, and Nikon’s options are

almost endless.


Speed Thrills

10 Sp

eed

Thrills

For action and sports photography when you’re trying to capture the critical

moment, it’s handy being able to fire off a rapid burst of shots. But high frame rates

are equally useful in portraiture, enabling you capture fleeting expressions when

speed is often of the essence

Continuous drive

Switch to continuous drive mode and your camera will keep .taking photos for as

long as you-keep your finger on the setter button. Buffer memory constraints

aside, continuous drive rates vary between about 3 fps (frames per second) on

the Nikon D3100 and a blistering 8fps on the Canon EOS 7D.

Other cameras come close; the Nikon D300S shoots at 7fps and this increase to 8

fps if you fit the optional MB-DIO battery grip with an EN-EL4a battery or fill it

with AA batteries, other cameras may enable you to boost the continuous drive

rate by disabling autofocus tracking and metering corrections during the

sequence

Processing power

To make the most of-high drive speeds, cameras also need to be big on

processing power, they can handle all the images in quick succession. The latest-

cameras’ image-processing chips are generally much more powerful than

models. Some cameras, such as the high-speed Canon EOS 7D), actually feature

two image processors for an even greater performance boost.

Buffer memory

Shoot in medium to high resolution JPEG mode and you can often maintain the

maximum burst rate of your camera’s continuous drive mode almost indefinitely.

Switch to raw image quality and it’s likely you’ll clog up the camera’s internal

memory buffer after just a few seconds. You’ll then have to play the waiting

game, while the buffer memory is written to the memory card — depending on

the speed of the memory cards you use, this can take quite a while slowing your

potential maximum frame rate to a crawl.



digital camera reviews - 10 things you need to know before buying a digital slr

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