Nikon reviews?

[Geoff]

I'm also glad that Bryan in including the comparison between the Nikon and Canon gear...but I'm a bit perplexed by exactly what you're looking at to draw a conclusion that xx canon lens is sharper than yy nikon lens.


Let me explain a bit more:


I pulled down the Canon 17-40L zoom at 17 mm and f4.0 and compared it to the Nikon17-55mm f2.8 if-ed af-s DX n lens set to 17 mm and f 4. Now that the lenses are set at the same f number and focal length, I would expect that the field of view should be identical for a valid comparison. Instead the Canon image is 50% larger than the Nikon image. Thus, I can't make a valid comparison of the two lenses! I would naturally expect the less expanded view of the resolution target to look sharper.


I understand that the two camera bodies may be at different pixel densities...but for a proper comparison, one camera (?canon?) should be down sampled, or the other camera (?nikon?) should be up sampled so that the same area of the target is compared.





Bryan in his explanation states:
<p style="padding-left: 120px;"]Why Do the Pattern Sizes Vary



While I go to great lengths to get perfect test shots, there may be very
slight variations in the framing of the tests (usually not more than a
few pixels).
I do not think these variances are enough to sway any comparisons -
otherwise I reshoot the test.
Still, some graphics in the test crops vary in size.
What you are probably seeing is lens distortion.
<p style="padding-left: 120px;"]


Perhaps someone could write a quick paragraph as how to properly use the resolution charts to augment what Bryan has already written...particularly when the field of view changes so drastically.


It would be a great help to us newbies!

[neuroanatomist]

...I'm a bit perplexed by exactly what you're looking at to draw a conclusion that xx canon lens is sharper than yy nikon lens...Perhaps someone could write a quick paragraph as how to properly use the resolution charts to augment what Bryan has already written...

I think the point is that you cannot draw such comparisons using these charts. If you look through the Canon lenses, you'll find some shot with both FF and 1.6x crop bodies, and the apparent fields of view are quite different. If you read elsewhere in the About ISO 12233 Charts page:

Lenses should be critically compared to each other only with test samples from the same camera body as it is the combination that is tested. Camera can be critically compared to each other using the same lens(theCanon EF 200mm f/2 L IS USM LensandCanon EF 200mm f/2.8 L II USM Lenshave results from many cameras included)...

Most of the Canon lenses are shot with a 1DsIII body, so they can be compared to one another. Bryan indicated two lenses which have been tested with many (Canon) bodies, so you can compare the bodies. I think all of the Nikon lenses are tested with a D3x - meaning that you can fairly compare those Nikon lenses only with one another, and not with Canon lenses.


At least, that's how I interpret it.