I have a Canon Direct 5D MK II refurb on order.

Started May 24, 2012 | Discussions thread
Timbukto
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Here is 85mm vs 55mm of 17-55 2.8
In reply to Y0GI, Jun 1, 2012

Both handheld so IS advantage going to t3i if there really is any at this shutter speed.

I had to lower the exposure in post on the 5DMK II...it overexposed compared to the t3i IMO. Resized to 2048 on long edge, very slight LR4.1 sharpening on both.

Here are my preliminary findings...5dMK II + 85mm 1.8 at 2.8 is clearly sharper through almost the entire frame except for the lower right where it is noticeably softer (not a huge surprise I expected on FF and based on most websites that you do tend to get this on EF lens when shot wide). 17-55 2.8 + APS-C has less 'inconsistent' softness benefitting from smaller crop sensor and glass area, but overall softer throughout. Considering the 17-55 2.8 was shot with a tighter framing (more magnified), this really does show there is a jump in sharpness since the 5DMK II is shooting wider FOV in these shots. After resizing to 2048 however the differences are pretty minimal but you can still see hints of what I'm talking about at 100% crop.

Notice however that the sharpness on far left or far right falls off slightly on the 17-55 2.8 but are tack sharp on 85mm at 2.8.

Without any purple fringing correction, the 17-55 2.8 actually looks better with the black peppers, but also the 85mm at 2.8 has a more shallow DOF so obviously has more LOCA fringing as well. Very easy to correct in post with LR 4.1.

The moment you cut a resized jpeg or so the differences are more slight as these resized pictures show, but you can probably still see hints of what I'm talking about in sharpness differences.

Overall I'd say this is a great showing of the t3i both with its auto-ISO in manual mode, its great ergonomics for people without bear hands, and fantastic flexibility and overall quality of the 17-55 2.8.

Actually to achieve similar DOF I'd have to stop down, etc...again I'd gain even more sharpness and less aberrations doing this but would have to rely more on the 5DMK II's ISO performance or alter shutter speed, etc. Haven't tested high ISO yet.

RAW file size difference is 26.4 vs 22.2, but obviously handheld I did not frame the two to be exact so its only anecdotal.

Here are two 100% crops-

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Canon EOS M Canon EOS 6D Canon EF 50mm f/1.4 USM Canon EF 85mm f/1.8 USM Canon EF 200mm f/2.8L II USM +1 more
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