So there we have it, then 7d isn't just a little better than the cropped 5d II. It, not only 1.6 better, not only 1.9 times better, not only 2x better, it's a full 2.25 times better.
But wait, can it even be better than that? Well yes, you see it's frame rate is double the amount of frames the 5D II will do, so 2 times as many pictures at 2.25 times the resolution means you get an average of 4.5 the resolving power of the 5D II.
How in the world did I not notice such a wide advantage when I was using it?
Camera shake? Tripod shake? The 7D has one of the smallest DSLR pixel pitches, only surpassed by Sony's 24mp APS-C sensors (which are actually 1.5x crop, so the difference is not as much as it sounds.) Like people have been saying about the D800: It really shows the lack of quality in your glass. Same goes for the 7D, only more so. At 100% crop, while the 7D WILL have more detail than the 5D II, unless you have the best glass money can buy that offers an MTF to match, it'll appear a bit soft. I don't think it has anything to do with an overly strong low-pass filter. I think it is simply that you need an order of magnitude better camera stability (along with a great lens) to produce ultracrisp 100% crop output like the 5D II can. The 5D II, with its 2.25x larger pixels, is somewhat forgiving. The 7D is entirely unforgiving. Normalize image size, either direction, in a focal-length limited scenario and the benefits of the 5D II IQ will largely disappear (although not entirely...it definitely has better very high ISO performance...i.e. ISO1600+ performance).
I own the EF 100-400mm lens and use it for my bird photography. I also rented the new EF 300mm f/2.8 L II IS a couple months ago. Even with a 2x TC attached, the 300mm lens (@ 600mm w/ 2x) blew my 100-400 to smithereens. There was zero contest...Canon's latest glass is almost an unholy level of good. With the 1.4x TC for 420mm, it was like a match made in heaven with the 7D. The results were unbelievable. I used to blame the 7D for my IQ problems. Now, I blame the 100-400mm lens. Don't get me wrong, it is a great lens, but its an old lens, and its age most definitely shows when used on the 7D. I'd say any lens not a recently released (post-2009 release) and a Mark II generation with 4-stop IS at least (if it has IS) will show its age with a 7D.
It is up to each individual to decide if THAT particular trait of the 7D, its unbelievable demand on lenses, is a positive or a negative. The 7D has the potential to trounce even the 1D X for reach and detail, but you would need a kit so expensive you'd probably feel like a twit using the 7D with that kit. ;P
Well, actually I wasn't that serious.
But you are correct about the supertele's. While the new II versions are super sharp, so were the old versions. The improvement with the new 2x convertor is great as well. I have the version I 300mm f/2.8 and 500mm f/4. The 100x400 can't even be considered in the same class with these lenses. Just like the difference you saw with the lenses, the 7D and 5D II are not even in the same class with the 1D IV, not just in AF but in many other ways.
The 7D and all crop bodies do have draw backs when photographing wildlife, because it seems we always give up something to gain something. We gain some resolution and AF ability over the 5D, (Not 4.5 times the resolution though and not a full 2.25 either ). Then we loose some some of the range we have with DOF. We loose some of our light which makes it a harder battle when trying to get enough speed and keep the ISO low. Our range of ISO is much tighter because of noise, most wildlife moves in the early morning or evening and this makes those times tougher. The 7D picture files tend to have a flatter appearance than the 5D II and most certainly the 1D IV's, creating that illusion of depth (the 3D look everyone talks about) is much harder to create with the 7D than the other two bodies. Then there is the Post Processing, with a 7D file I have to work it to make it all it can be where the 1D IV I almost have to do nothing.
Here is probably a big reason that the 7D isn't all that the specs make it out to be. I believe the 7D sensor is a fine sensor however I also believe that Canon has purposely dumbed down the files from the 7D with their firmware so that it would not produce files that initially come out looking better than the high end bodies. Notice the 1D X vs 1D C debate going on in another thread, and the complaints that they feel Canon is charging $6 to $7K more for just firmware.
While I agree about the 7D photos looking a bit drab right out of the camera, I wouldn't go so far as to blame canon directly for explicitly making it so. The 1D IV has about twice the maximum saturation point as the 7D, and the 5D III has about three times the maximum saturation point of the 7D. That leads to a much higher S/N, which leads to richer results and less noise at all ISO settings. I also believe the 7D has a slightly weaker CFA than the 1D IV (although the 5D III also has a weaker CFA), which is more about improving S/N as much as possible with those tiny pixels than purposely drabifying the output.
Personally, when I've used a 5D II, I felt it's color output was also a little drab too, although not quite as much as the 7D. The 1D IV RAW files I've played with all felt much richer, in every aspect (especially tonality, shadow falloff), than any other Canon camera I have used, by a significant degree. Canon intentionally puts more
effort into the 1D series of cameras, so it should be expected that they would put more effort into every aspect, including IQ, over the cheaper relatives. I suspect that the lower quality of Canon's non-1D cameras is more a facet of their cheaper cost, and less intensive per-camera quality control and fine craftsmanship than you get with the vastly more expensive 1D bodies. I have not used a 5D III, but from what I can tell, its native camera output is more becoming of its price tag, so maybe Canon is starting to put more effort into their second-ranking cameras now (and I wouldn't be surprised, given the kind of competition they are experiencing from all sides).