FF Effect on Lenses

I was just reading a review of the EF 70-200/2.8L IS lens at DPReview, and what is astonishing is that the lens performed MUCH better on the full frame 5D than it did on the 1.6 crop cameras.

http://www.dpreview.co​m …on_70-200_2p8_is_usm_c16/

Their explanation for this is:
"However this excellent full-frame performance does come at some cost to APS-C users; perceived sharpness is reduced (due simply to the extra magnification imposed by the smaller sensor), and this amplifies the impression of softness wide open."

But this seems contrary to what I've always lead to believe. That a crop should be using the "sweet-spot" of a lens and produce better results.

Ironically, in their review of the nikon 70-200VR, the lens performs extremely well on their crop cameras (1.5x) but relatively poorly on the full-frame D3 (lagging behind the Canon counterpart by a fair margin).

As a side note, what was nice to see was the fact that Canon's IS dominated the VR technology by a fair amount.
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Canon IS results:

drisley wrote in post #5549801
I was just reading a review of the EF 70-200/2.8L IS lens at DPReview, and what is astonishing is that the lens performed MUCH better on the full frame 5D than it did on the 1.6 crop cameras.

Makes sense to me. With a full frame, there is less magnification of the final print. Plus, the pixel density would usually be greater on a crop camera putting more resolution demands on the lens.

Yeah, that's how they explained it too.
But often I hear the opposite. That FF is more demanding because it uses the whole lens, not just the sweet spot at the center.

drisley wrote in post #5550069
Yeah, that's how they explained it too.
But often I hear the opposite. That FF is more demanding because it uses the whole lens, not just the sweet spot at the center.

I guess it goes both ways - You get the sweet spot with a crop sensor, but with greater pixel density...

On the other hand, with ff you have less pixel density, but you also get the corner softness. You take the good with the bad with each one.

This is it really.

When people say that the crop formats only use the 'sweet spot' they are referring to the cropping off of the corners. Some lenses, especially cheaper wide angle lenses have soft corners. OTOH, corner performance is usually only really demanded by landscape photographers. Most photography has OOF regions or non-subject material far into the corners. Portrait photographers for instance usually don't give a rip about the corners at all.

The flip side is that larger formats require much less lens resolution across the entire frame for the same final print quality. This comes down simply to the reduced degree of enlargement. So a lens/FF combo that performs with an acceptable MTF at 30 lines/mm needs to be matched by a lens/1.6 combo that can post the same MTF at 48 lines/mm to be equal.

It looks like Nikon boosted center sharpness on their 70-200 to hold up to the increased magnification of their 1.5X sensors and let the corners go. At the time the only victims of that strategy were Nikon film shooters. Now D3 buyers are also suffering.

I can attest that the Canon 70-200/2.8 is a cracker on FF.

Perhaps this is an advantage of 1.3x crop 1D
The best of both worlds

drisley wrote in post #5550219
Perhaps this is an advantage of 1.3x crop 1D
The best of both worlds

Or is 135 format the best of both worlds between 1.3 and 1.6X vs. Medium format digital backs?

One of the biggest problems that arises when you start to talk about advantages / disadvantages of the various formats we use is that people get hung up on pixel density, total pixels and pixel size. It's like all the people who chant "glass before bodies" as a mantra then immediately forget that the point of glass is resolution on the sensor, and the more you enlarge that image the more it matters.

If you are after maximum resolution, there are almost no circumstances where a smaller format is better. The only case is when you cannot obtain / afford a long enough lens and you have to crop hard. Then the generally higher pixel densities of the smaller formats are helpful.

JeffreyG hit the nail on the head with his answer.

I was all geared up to type a bunch of stuff too, but the man once again saves me the effort with an excellent reply .

drisley wrote in post #5549801
I was just reading a review of the EF 70-200/2.8L IS lens at DPReview, and what is astonishing is that the lens performed MUCH better on the full frame 5D than it did on the 1.6 crop cameras.

http://www.dpreview.co​m …on_70-200_2p8_is_usm_c16/

Their explanation for this is:
"However this excellent full-frame performance does come at some cost to APS-C users; perceived sharpness is reduced (due simply to the extra magnification imposed by the smaller sensor), and this amplifies the impression of softness wide open."

But this seems contrary to what I've always lead to believe. That a crop should be using the "sweet-spot" of a lens and produce better results.

....

Does not surprise me much, it is a trade off between how much sharper the center and borders of the lens is. If the edge/corner is less than 1.6X softer than the centre then you are better off with full frame.

JeffreyG wrote in post #5550296
Or is 135 format the best of both worlds between 1.3 and 1.6X vs. Medium format digital backs?

One of the biggest problems that arises when you start to talk about advantages / disadvantages of the various formats we use is that people get hung up on pixel density, total pixels and pixel size. It's like all the people who chant "glass before bodies" as a mantra then immediately forget that the point of glass is resolution on the sensor, and the more you enlarge that image the more it matters.

If you are after maximum resolution, there are almost no circumstances where a smaller format is better. The only case is when you cannot obtain / afford a long enough lens and you have to crop hard. Then the generally higher pixel densities of the smaller formats are helpful.

Thank you, Jeff. It is nice to have someone else making those statements because I get tired chanting that same mantra.