Progress made with in-camera noise suppression and high-sensitivity performance means that APS-C-format cameras now produce larger, better-quality images than ever before. Angela Nicholson looks at the Canon EOS 7D and EOS 5D Mark II to see whether full frame still holds an advantage.
Everyone likes to hear a David and Goliath-type story where two seemingly unevenly matched opponents clash and the minnow comes out victorious.
For photographers, the possibility that a small-format camera can produce similar (or even better) quality images to a model with a larger sensor is enticing on several levels, not least because the smaller sensor size usually makes the camera more affordable.
As such, there was quite a bit of excitement when our test of the APS-C-format Canon EOS 7D revealed that it produces images that give the full-frame EOS 5D Mark II a run for its money.
In this test I’m going to see if the new generation of APS-C cameras really can produce the type of quality we have come to expect from full-frame models. The EOS 5D Mark II and EOS 7D will be the main focus, but I’ll also compare the results from the Nikon D3S and D300S, and the Sony Alpha 850 and Alpha 550, and look at the pros and cons of full-frame and APS-C-format photography.
How we match composition to compare cameras
There are essentially two ways of matching the framing of images when shooting with APS-C-format and full-frame cameras. The first is to have greater distance between the subject and the APS-C-format camera than with the full-frame model. The second is to adjust the focal length so that the effective angle of view is the same on both cameras. I used both of these approaches during this test to produce comparable images.
Canon EOS 5D Mark II
Canon’s EOS 5D was the first camera to make full-frame digital photography possible for many enthusiast photographers. It allowed them to use the lenses they had been using on their Canon 35mm film cameras and see exactly the same composition in the viewfinder. The larger sensor also allowed room for bigger photoreceptors so, in addition to having a greater pixel count, the camera could produce images with less noise than its APS-C-format counterparts.
It’s worth remembering at this point that sometimes it isn’t the amount of visible noise that is a problem for image quality, but the level of noise reduction that is applied to the files. Canon has in the past been guilty of being a little too liberal with its noise-reduction algorithms, and some of the EOS 5D’s APS-C-format contemporaries were prone to producing rather soft JPEG files as a result.
As it sat just on the right side of affordability (in comparison to Canon’s EOS-1D-series DSLRs), the EOS 5D was a big seller and was popular with professional and enthusiast photographers alike. However, after around three years it was starting to look a little dated and in September 2008 its replacement, the EOS 5D Mark II, was unveiled.
With the possible exception of its HD video capability, this camera’s specification was fairly predictable, and the upgrade was primarily about bringing the camera into line with Canon’s other DSLR offerings with the inclusion of Live View technology, a sensor cleaning system, 14-bit processing, Highlight Tone Priority and Auto Lighting Optimiser. The increase in pixel count to 21.1 million effective pixels and the Digic 4 processor could also have been anticipated.
One significant change from the original EOS 5D, however, was the ability to expand the native sensitivity range from ISO 100-6400, to include settings equivalent to ISO 50, 12,800 and 25,600. This highest setting, which is now trumped by the ISO 102,800 of the Nikon D3S and Canon EOS-1D Mark IV, matched what was possible with high-end Nikon DSLRs at the time.
Canon EOS 7D
While the EOS 5D Mark II’s arrival had been anticipated for many months, the EOS 7D came as a surprise to many. It isn’t an upgrade or a replacement for an earlier model, but it usurped the EOS 50D’s position at the top of Canon’s APS-C-format line-up and is the first of a new series of Canon cameras with a single-digit name.
The camera’s specification also revealed a few surprises, suggesting that Canon has started to rethink some of its previous policies and was wanting to tackle the challenge raised by Nikon and, to a lesser extent, Sony. For instance, after saying for several years that it was unnecessary because of the existence of the Speedlite Transmitter ST-E2, the manufacturer finally conceded that in-camera wireless flash control is desirable.
The EOS 7D also debuted a 19-point AF system that borrows features from the EOS-1D Mark III to allow the photographer to customise its response to suit the subject, and the new Focus Colour Luminance (iFCL) metering system, which uses subject distance, colour and luminance information. In comparison, the EOS 5D Mark II has the same metering and AF systems as its predecessor with Canon’s well-established 35-zone evaluative metering system (backed up by centreweighted, partial and spot metering), and nine selectable AF points supported by six non-user-selectable auxiliary points.
While Nikon is firmly sticking to its guns that 12 million pixels is enough on an APS-C-sized sensor (and, with the exception of the D3X, on a full-frame device), Canon is a bit more ambitious in this respect. When the EOS 7D was announced, the prospect of images with 18 million pixels being produced by a camera with a 22.3×14.9mm (APS-C sized) CMOS sensor was both alarming and exciting at the same time. Although the images might be large, there was also the possibility that they could be very noisy – like the results from the EOS 50D – or suffer from the effects of heavy-handed noise reduction.
However, Canon employed a new sensor with less circuitry for the EOS 7D, which allows its photodiodes to be larger, helping high-sensitivity and dynamic range performance.
Canon also employed a new design for the diodes to allow them to convert more light into an electrical charge for a higher signal-to-noise ratio. The diode’s capacity has also been increased to reduce overloading in bright light and extend the dynamic range. As in the EOS 5D Mark II, the gapless micro lenses over the photodiodes sit closer to the photoreceptors, enabling more light
to reach the sensitive surface.
All these factors combine to allow the EOS 7D to produce significantly larger, cleaner and more detail-rich images than we have seen before from a Canon APS-C-format DSLR.
