UPDATE: I posted more thoughts on this subject and a reader’s comment Here.
So I just remembered tonight there was a full moon. I hurriedly pulled out my camera gear (it was already close to 10:30pm) and headed for the back yard. There were some nice clouds passing over the moon and I thought it should make for a great time lapse. Then wondered what camera should I use?? I remembered the 7D and my 70-200mm f/2.8 IS II gave me a spectacular image with the ease of a point and shoot. But that was over a year ago and now I have the 5D Mark-III. But then I thought it’s full frame sensor meant less coverage of the point in the sky (moon) I was trying to photograph. But it had a technically superior sensor and higher overall resolution. I thought this might be enough to match the high pixel density of the 7D.
I was wrong. This was one of the classic examples of a situation where the 7D is just a way better camera for the job hands down. Both shots were at f/4, ISO-100 and 1/1000 second. AF on and IS on (mode 1). At ISO-100, there was no advantage to the newer 5D Mark-III sensor. Both were right at home with the higher shutter speed. AF was spot on and on the 7D seemed a hair more confident/quicker than the 5D Mark III. Yes, I know the DIGIC5 processor is supposed to be 17x faster than the DIGIC 4 but as a software engineer I’m pretty sure having a processor dedicated to AF (7D has Dual DIGIC4 Processors) means parallel AF processing. In real life it’s either a wash or still a better performing configuration than a single DIGIC5.
This simple quick and rough test just confirmed my suspicions and what I’ve always tried to explain to some fellow photo geeks. Just because it’s a full frame camera does not necessarily mean it captures more detail in the true technical sense. The comparison here shows the 7D delivering the full moon with easily 2 times the number of pixels the 5D Mark-III and with similar clarity and sharpness using the same lens and settings.
I still maintain, for most other general scenarios and large field of view the 5D Mark-III will yield a superior image. However the 7D with it’s considerably higher pixel density will always yield much more detail (in this case, twice the detail). This is one of the many real life, real world scenarios that no ISO-Chart, spec sheet regurgitating blogging, rent-a-camera-for-a-weekend-reviewer will ever tell you. If you haven’t yet figured it out, I pretty much loathe most of the talking/blogging heads on the web just echoing whatever everyone else says.
This is one reason why I still hang onto my 7D. It is an amazing camera system. However it is imperative that a 7D owner only mount the best lens optics that money can buy because of the unforgiving and high pixel densities. The key is to know your shooting style, know and understand your camera system to make full use of it’s potential.
Yes I do own both camera systems and actively shoot both.