Hi Steve,
as the guy who sold me his 7D has erroneously given me wrong bank details (well, this kind of things can always happen....) I still haven't got my 7D yet which - in addition to having a slight cold right now - leaves me with some more days of reading reviews and test reports of lenses.... instead of going out and trying out things for myself ....
the 5D2 is another step above in both noise and resolution with all lenses (the pixel density is the same as the 20D)
I absolutely agree on the high ISO *but* I had the opportunity to do some shots with a 7D some time ago with my Tamron 90 macro and I must say, to all intents and purposes, at low ISO they just look absolutely identical on a 100% level to those of the 1Ds2 (I had also made the same shots with the 1Ds2). There's the same amount of details, no difference that I could ever see. And the 1Ds2 itself I did compare to the 5D2, again - to my eyes - same quality at 100% level. So it's just 16 vs. 18 vs. 21 MP, well 18 vs. 21 is not really a difference that I care for.
The 7D loses big time in the high ISO department - again *but* it wins big time, at least when shooting macros - in the depth-of-field department. So for all my macro work I am really sure I will end up with the same file quality (resolution, noise, everything else....) than what I've got with the 5D2 - save, of course, for the little 21 vs. 18 MP difference.
For telephoto stuff the 5D2 would again win with, say a 500/4 vs. the 7D with a 300/4 - because if I have both lenses at f/4 and the same shutter speed on both cameras, the 5D2 high ISO quality is better. But I will probably never ever have a 500/4 lens, it is way to expensive and also way to big and heavy.... so what I'd ended up is having a 300/4 plus 1.5x converter on the 5D2, and in effect that means losing all the theoretical 5D2 advantages over the 7D.... I then have only f/5.6 or so, I have some image quality loss due to the converter, I don't get any better files than what the 7D with the plain 300 without converter can give me.
OK you can argue, the 7D does - on the other hand - *not* give any image quality improvements. But for me, it's just so much easier to work with it. I can get macro down 1:1 size - thats 22x15 mm (instead of 36x24 mm) without any need for extension rings, converters or the like. Without any attachments, the 300/4IS focuses down to 1:4 size - and again 1:4 is a very different story on the 7D than it was on the 5D2. That way I can shoot happily e.g. all dragonflies without any extension rings or the like.
That's all sooo much less fuss than it was before.
5D2 and 24-105 is a great walk-around combination - comparable in size and weight to a crop-frame with 17-55 but with a more useful zoom range
the 100-400 is heavier but not a lot longer (collapsed) than the 70-200 f4 and i find it much more useful (i tested the 70-200 and resolution is very good, but seriously degraded by the 1.4x).
the 17-40 is a good lens but i will probably replace it for travel with a Voigtlander 20mm --
I have thought and looked back at all the images that I've taken with the 24-70L on 5D2 / 1Ds2 so far. In fact, I found myself always carrying the 24-70L *and* the 100-300L, because the 24-70L lacks any telephoto range. The 17-55IS might be a little longer but its lacking again. I guess most of my shots are either (on full frame) 24-50 mm *or* they are at 100 mm or above. Apart from dedicated portrait shootings (which I sometimes do for work) I'm almost never using the 50....100 mm range. With the 24-70L I of course have taken some shots at 70, but often cropped those afterwards.
This - and the worry about long-term reliability - has again brought me back to the 17-40L. It covers the full frame 24-50 range anyway for me. It's not a low DOF specialist but what the heck, there's always some little spare space for a prime.
The alternative would be a 18-135 or something like that which would be a *really* nice zoom range but then the quality of lenses like that, sadly, is not what I am looking for.
Now that you mention that Voigtländer lens, I've never heard of that one.
Regarding the 100-400L, I've never tried one so far. I guess it'll be to heavy for me. I had some opportunity to use a Canon 70-200/2.8 and Tokina 80-200/2.8 and frequently found myself leaving them at home. If I am willing to carry such a heavy lens, I'd probably rather take the fixed 300 then.
wildlife - used the crop frame cameras with 100-400 to get 640 equivalent (400 just isn't enough) but found no difference to the 5D2 and an equivalent crop (and with anything shorter the 5D2 is better). Intend to try a 7D with 400 f5.6 in a month or so and see if there's a useful improvement - anybody tried this?
My guess is you'll never find any cases where the 7D will deliver *better* IQ than a 5D2.
The point is - at least to me - there are a lot of cases (some of which I've described above) where the 7D will give *the same* IQ but with more convenience. It's not just the crop factor which eliminates the need for extension rings, or teleconverters, it's of course also the nice 7D body with the - to me at least - more comfortable viewfinder (big EOS 1 series viewfinder design - the 5D2 is more "20D" style where I found myself frequently smearing my nose against the rear screen), also the advanced autofocus, stuff like that....
That's why I now am switching to the 7D.
I was always perfectly happy with 5D2 or 1Ds2 IQ and not looking for more quality. But I am definitely looking for more convenience, less weight in the camera bag, yet still achieving the same picture quality.
The only thing where I really see the 7D in advance even regarding image quality, is that you can now enjoy using the 70-200/4L .... which is a so much better lens than the 70-300DO or all the other Canon xx-300s on the full frame bodies.
cheers,
Thomas