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Comparing EOS 5D MARK2 versus EOS 7D and vs. EOS 30D at high ISO (ISO6400),
about noise, detail preservation, image quality, dynamic range
As always I run the test in a not scientific manner but simply aiming to highlight some aspects that I think are important in determining the choice of a camera or a lens, based on my personal needs. I have to decide whether to chose as second body to my Eos 5D Mark2 an Eos 7d or keep the current Eos 30D.
I've never used an Eos 7D, I would say that it is the only Canon camera in the area of semi-pro and pro that I never had in my hands once. Given the many threads about this camera, which can be found on the net, with absolute detractors and others who worship it, at the end I started to have serious doubts about the quality of the files produced by the 7D. In general, I am convinced that too many megapixels of nowadays cameras are only an problem, and very little do to the actual quality of an image. I also wanted to see if this marketing has even gone so far as to produce a camera with a density of pixel such to be worse than a precursor as the 30D, with only 8MP. In general I do not believe this, among other things, 18MP has now become the standard for all APS-C cameras from Canon.
I read around very bad things about the 7D: that it produces very soft files, that the autofocus fails, that as you just raise the ISO it produces a lot of noise and loses details, that eventually it has an image quality equal to an entry-level camera . Well, unless my student who has just became owner of a 7D has been particularly lucky, by having received a copy better than others, or maybe just thanks to the recently updated firmware, the fact is that by exploring this camera, now I would say... bullshit!
I understand even more as much the inexperience and indeed real ignorance of many makes so that the camera is charged for their blunders. The EOS 7D's autofocus if set on maximum accuracy, in one shot mode, is as precise as a razor. The 7D does not produce files softer than other cameras when shooting in RAW and the same photographic processing is applied to images.
As quick test we compared the detail on the area in semi-shade (left eye) of a portrait, executed with an EOS 30D, EOS 7D and an EOS 5D Mark2, at well ISO 6400. Obviously, the EOS 30D does not have the ISO 6400 but just shoot at ISO 3200, RAW, and then raise exposure by 1 stop right in Camera RAW. I present to you the 100% crop of the three shots and then I'll make my comments. As it is standard for this type of comparison, I have NOT reduced the files from cameras with higher resolution but up-resized the lower resolution ones up to the largest size, in our case, the 21MP of the eos5D, or 5616 pixels on the longest side. The crop 100% means that this image at 700px corresponds to the detail taken as 100% magnification.
Conclusions
For all three pictures we used a EF 85mm 1.8 USM @ f4, to get the best quality from the optics.
In our crop, what we see is indeed the noise from the camera set at the highest ISO (6400 ), but also the preserved details, colour and dynamic range. We present therefore the partially shaded eye of the portrait where certain differences are more noticeable. A partial recovery on the shadowed parts guarantees to better highlight the limits of the dynamic range of each camera. The lowerer DOF of the full-frame at F4 (identical for all three shots), makes the photo of EOS 5D slightly softer (the focus is on the right eye, not the left), but I assure you that level of sharpness on the focal plane of all three shots is identical.
What you need to look at is instead the iris of the eye, the nuances of colour, the details inside. Clearly the EOS 5D Mark2 is a notch above the other two, as one might expect from a sensor that has virtually half the density of photodiodes with respect to 7D, but not with respect to 30D. The EOS 30D as old as it remains, is still a good camera. Do not be fooled by advertising, its field quality is very high even today, especially if you use good optics. Files from the 30D when enlarged can almost match with a camera like the EOS 7D, even at ISO 6400 that are not available in the EOS 30D (actually a firmware update would be enough to have them, but of course the Canon is careful not to do so).
The image produced by EOS 7D is still better than the EOS 30D’s (always look at the iris of the eye), but not the same jump that you have on EOS 5D2. This is still a great result for the EOS7D, that ISO 6400 and 18MP have less noise and more detail and in shades and colour. Really good result.
This small test teaches us another thing: if we compare a file of 8MP and 18MP the real difference of magnification is about 30% (not double as one might expect). If you enlarge a file like an 8MP to 18MP, the difference in detail is really ridiculous; such a file if correctly processed and printed would produce no perceptible difference. What are then the 18MP of an EOS 7D good for, apart from the advertising? Well we actually need those, but not if we use the photos at 100% magnification. That is, if we do not need to crop the photo since we can get optically close enough, then between 8 and 18 the difference is virtually ZERO! But sometimes crop is unavoidable, for example in the photo of fauna and for sport. So then when a file is cut 50% to 4 MP or 9MP things get very different. The 9MP file still has lot details to make large prints, the other one begins to suffer a lot, at 4MP (still usable, with the right processing).
Canon EOS 7D while doubling the number of pixels and increasing by 30% the resolution still maintains a level of noise even less than 30D, this is definitely a great achievement and I would say not at all due to the noise reduction applied by the software, the files are in fact identical in Camera Raw in terms of sharpness. On final word, the EOS 7D is an excellent camera, even if image quality is not very much better than a 30D’s or 40D’s. You choose it for many other reasons: resolution to crop, as said, but also a high-performance autofocus in sports, a great construction and excellent sealing, the flash that remotely controls other flashes, etc. etc… in short, many other things that "make the life of a photographer better". Even to use it is a real joy, much better even than EOS 5D, in comparison 30D looks as a plastic toy (it is not). But:
if you do not take pictures in rain, for sport, wildlife, etc.., and you've purchased the EOS 7D to take pictures on vacation, convinced that the hundreds of euro more you paid will ensure you better photos, then you've got a blunder, commercially induced, but a blunder. The 7D is great, but only IF you use it at its maximum, in sports and / or wilderness area, then it really pays you off. Here's how some lamentations were born!
In another test, run against EOS 30D + EF 85mm 1.8 but at aperture of 5.6 and the same pose, we coupled the EOS 7D with a Canon EF 15-85 @ 85mm and aperture 5.6 (minimum that is allowed by the zoom at 85mm). Well despite the 8MP against 18MP, the 30D+85mm prime brings out more details, or rather: BETTER LENSES PRODUCE BETTER IMAGES DESPITE THE LOWER RESOLUTION OF THE SENSOR. Mind that the EF 15-85 is a great zoom lens and the picture it produced is sharp, but the quality that you get with a prime even on an old camera is higher, namely: EOS 30D (used) + 85mm 1.8 costs about 700 euros, the EOS 7D (used) + 15-85 almost double it. Obviously they are very different set-ups for different purposes, but everyone can draw his own conclusions.
©2012 Marco Palladino – All rights reserved
I have an Eos 5D Mark3 since few months, it replaced the Eos 5D2 I used in India that had partially left me because of poor weather sealing giving problems to the contacts. I always judged with some reservation the image quality of the 5d line , coming from the 1Ds mark2. These cameras do produce excellent images, but some really bizarre problems in cameras of this level do continue to appear. 
