BenMont wrote in post #14533171
Is this from your own experience (with or without a TC)? AF speed and accuracy are the top factors for me in the decision to purchase this lens, and I'm having a hard time making my mind up!
Also, looking at the ISO 112233 crops, it seems the 100-400 is a lot sharper in the corners at 400mm F/5.6 compared to the Sigma at 420 F/5.6 (with a 1.4). I know yourself and Gabe have said that you reckon your copies are sharper - again, is this with or without TCs?
Ben, (and guys) Here is a 300mm f/2.8 wide open montage: Here is a 300mm f/4 montage: Now, here are the resized versions:420mm f/5.6 300mm f/2.8: 300mm f/4:
Here are some unscientific res chart crops that I made this morning.
Please note that my chart's resolution is different from TDP's.
PLEASE READ THE NOTES BELOW BEFORE LOOKING AT THE IMAGES (not yelling here just drawing attention )
My setup: 7D, 120-300 2.8 OS, Velbon tripod, and a self-printed res chart on a 19x13 paper. Mirror lock-up, 10 sec timer, live view 10x manual focus.
These samples show a montage of 3 images consisting of: center 100%, off center 100%, and a corner 100% crop (from top to bottom in the montage).
First 3 images are direct crops from the 18mp 7D image, which we all know is pretty mercyless on lenses due to the high pixel density (equals to a theoretical 40mp full frame sensor).
However, since it's a crop sensor, my corners are going to be better than corner crops from a full frame camera.
Please note that I applied some sharpening on these crops.
The last 3 images are resized versions of the first 3, resized to simulate the pixel density of a Canon 5DII or 1DsIII (21 mp). Their 21 megapixel sensor's pixel density equals the pixel density of a 8mp APS-C camera such as the 20D or XT for example. So I resized them to simulate an image that would have come from a sensor with the pixel density of a 5DII, 1DsIII, 20D, or Rebel XT (350D). Obviously, they are sharper.
However, I cannot simulate corner crops from a full framer since I do not have a full framer (somebody want to gift me a 5DIII for my tests? )
For Ben, here is the 420mm f/5.6 montage using my Sigma 1.4x APO EX DG:
As you can see, the 1.4x TC does not affect IQ too much which is a good thing.
I also did not correct vignetting.
I'm not sure how all this compares to TDP's copy, or other top lenses (Canon 70-200 2.8 IS II, and the big telephoto primes), but for the price it is awesome.