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Skip Navigation LinksPC Authority > Group Tests > Digital SLRS - 11 models tested and reviewed
Digital SLRS - 11 models tested and reviewed
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Digital SLRS - 11 models tested and reviewed

by David Fearon  on Nov 21, 2008
Tags: Digital | SLRS | | 11 | tested | and | reviewed
DSLR Lenses

Probably the greatest advantage of an SLR camera is the enormous range of lenses you can use. At the basic level it simply allows different focal lengths, ranging from super-wide-angle to extreme telephoto. But there’s more to consider than just that.

Maximum aperture is a big part of a lens’s specification, and the wider the maximum the more expensive – and heavier – the lens will be. A kit lens typically has a maximum aperture of f/3.6 at wide-angle and f/5.6 at full zoom. A good aftermarket lens might offer f/2.8 across the whole zoom range.

Digital-specific lenses

Most new lenses for SLRs are now slated as being digital-specific. There are two aspects to this. Many are designed for cameras with APS-C-sized sensors, rather than full-frame 35mm. This is an important limitation, since they’re designed to project an image circle that covers only the smaller size of an APS sensor.

If you attach a designed-for-digital APS-C lens to a 35mm film camera, or a full-frame digital camera such as Canon’s EOS 5D, the result will be severe “vignetting”, with darkened corners to your images. Designed-for-digital lenses also use different coatings on their glass elements. This isn’t merely a marketing ploy to get you to buy more expensive lenses.

Digital cameras are far more prone to the effects of light bouncing around inside the lens and the camera body, because of the construction of digital sensors. To maximise the use of all available light, every pixel element of a sensor is covered by a micro-lens. These tend to pick up indirect light readily, leading to light contamination and unwanted flare effects. Digital-specific coatings are designed to absorb that stray light, reducing its effect.

In recent years, the technology behind zooms has meant that the best are extremely close in terms of quality to non-zoom “prime” lenses, and the convenience factor means new prime lenses are produced very rarely. That said, most serious amateurs and professionals still have three or four lenses in their kit bag. You’ll usually find a zoom covering the wide-angle end of the spectrum, perhaps around 10-22mm; a “middling” zoom that will cover most everyday situations, typically around 18-70mm; and a telephoto for things like wildlife photography, the most common range for these being 70-200mm or 70-300mm.

Super-zooms

A relatively new class of lenses is known as the super-zoom. The aim of these is to replace a whole bag full of lenses with one that covers the whole range of focal lengths from true wide-angle to telephoto. The first generation of super-zooms had a range of 18-200mm (28mm-320mm equivalent). Models with this range are available from Canon, Nikon, Sigma, Tamron and others. As the technology has progressed further, the range has become extreme – Tamron has an 18-270mm model, which is equivalent to a 15x zoom range.

While a super-zoom can make a great carry-around lens that’s ready for any situation (they’re particularly good for holidays where you’re not able to take your whole kit bag), they have their drawbacks. First is the fact that they’re not especially fast, usually f/3.5 at wide-angle to around f/5.6 at maximum telephoto.

That means depth-of-field effects can be more difficult to achieve, and low-light photography without camera shake can be difficult, too, especially at maximum zoom where the aperture is at its minimum and camera-shake is exacerbated by the magnification factor.

To mitigate the second of those effects, newer super-zooms feature image stabilisation. Second, because of the large number of glass elements in a super-zoom, there’s more chance of unwanted effects like flare and ghosting.

Identifying lenses

The primary way of distinguishing between different lenses isn’t by model name or number, but by focal length and maximum aperture. Beyond that they often have various prefixes and suffixes indicating their relative quality and features.

You should bear in mind that lens names are very precise, and some are so similar it’s easy to become confused. For example, Canon until recently had two different 70-300mm zoom lenses. One was called the 70-300mm f/4.5-5.6 IS USM; the other the 70-300mm f/4.5-5.6 DO IS USM. The DO version
This article appeared in the December, 2008 issue of PC Authority.
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Comments: 2
Thoughts on this article? Add a comment below.
chrishoward
Feb 18, 2009 9:44 AM
I just don't get your reviews. They seem to value the wrong things. This one is a classic example.

Your table shows the two Canon cameras at the top of the list for picture quality and the two Sonys at the bottom.

And yet you recommend the Sony a200.

Picture quality is the most important thing when buying a camera. If the quality isn't up to scratch, then why buy?

I researched this thoroughly last month when I bought a DSLR and (on my budget) kept coming back to the Canon EOS 1000D and the Sony a200. However, every test I saw of the Sony, the picture quality was noticably worse. More picture noise at low light levels, and much more chromatic abberation. And likewise, I too found the Canons had better picture quality than anything else.

The a200 did not have acceptable picture quality compared to other cameras - as validated by your table.

So how can it be your recommended camera when on picture quality, the most important aspect of its usage, it rates poorest?

Along with the recent review of smartphones where you recommended the most expensive with a more difficult interface and only marginally better specs than alternatives, I find your reviews lack credibility, and dare I say it, objectivity.



Comment made about the PC Authority article:
Digital SLRS - 11 models tested and reviewed?
They may look big and complicated, but a digital slr is just as easy to use and takes far better pictures than a pocket digicam

What do you think? Join the discussion.
phototext
Feb 21, 2009 9:52 AM
First up, so there is no confusion for those new to photography, chromatic aberrations are the result of a poorly designed lens, not the camera (film or sensor). But, as the reviews include lenses as a kit, something to consider.

I disagree with the premise that photography is all about "quality". A fluid term at best when discussing photography. If quality was the only measurement for judging a photograph we would all be shooting film on a Hasselblad or god forbid, dragging around view cameras and Holgas wouldn't exist.

Photography is a broad church, one persons requirements may not meet the needs of another. Hence, the wide variety of cameras, functions, lenses etc etc. The cameras and lenses I use would be a waste of money for many people, the output quality far exceeding anything they need. Their money would be better spent on other things.

For the majority of people purchasing at this price level quality is secondary to value and any of these cameras would produce images beyond their skill levels. Great images are not the result of a camera but of a great photographer. The better the camera, the easier it is, but how many people purchasing a camera at this price point are looking to create technical masterpieces, very few. The quality of the output from all these cameras would easily match their expectations.

Most will be looking for something that is a step up from a P&S, all these cameras are better than the majority of non DSLR (digital) cameras, and the Sony is very good value for this crowd.

Noise and sharpness are relative to intent, if you want to view an image at 200% on a monitor to see a lack of noise at ISO 1600 buy a D700. If your intent is to capture Auntie May cutting the cake, the kids playing with the dog or a nice sunset and are posting the images onto Flickr or to print out some 8x10's for the family album then all these cameras will do a stand up job.

Quality is relative. Intent is foremost. Content is king.

"Picture quality" is not the most important aspect of a camera, it is one of many factors in making a camera purchase decision. I think they got it about right, the Sony for that balance of quality and value and the 450D for quality.

In much the same way that you made a judgement on various factors with your recent camera purchase, balancing features, value and quality for the price you can afford. I'm sure you would have liked to have purchased a Canon EOS 5D Mark II or a Nikon D700 and spent several thousand dollars on some nice glass, but would it have been a good use of your hard earned money and would the quality of your images be any better ?

Don't get too wrapped up in using noise and sharpness as a measure of how good a photograph is, that way leads to disapointment and stagnation. Most people when they view a photograph don't care about noise and sharpness, they care about the moment captured.

Have a read of On Photography by Susan Sontag, you can learn more about photography in that little book than a room full of technical manuals and it is a lot cheaper than a Canon EOS 5D Mark II.


Jeremy Russell

http://1x.com/member/1148/jeremy-russell/






Edited by phototext: 21/2/2009 10:10:56 AM
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