GMCPhotographics said:
AlanF said:
This what the difference in MTFs of the 400 f/2.8 II at f/2.8 (top) and the 400 f/5.6 at f/5.6 (bottom) mean in practice as measured by SLRgear's blur tests.
I do question that 400mm f2.8 lens test....we all know it's a more capable lens than that, I suspect there is a flaw in their testing method for longer lenses. It's a comon issue with lens tests...the photozone.de lens test of the 300mm f2.8 IS L was laughable...it suggested that it was no better than a consumer zoom...and subsequantly the review got pulled, but some of us still remember it.
I have a 400 f2.8 L IS and I had until recently a 400mm f5.6 L, they are both very sharp lenses but the f2.8 is in a different league.
That's interesting. Part of my reasoning for saying that I don't trust the results of the SLRgear test is that when you go to Photozone.de and compare the 400f5.6 wide open with the 40mm Pancake at f16, the Pancake at f16 should be obviously worse than the 400f5.6. Now go compare that with the SLRgear tests, according to them the Pancake at f16 is far superior to the 400f5.6 wide open.
Someone doesn't have their numbers straight. To get an average, when I look at the TDP charts the 400f2.8ISII and 400f5.6 "look" nearly identical wide open.