01-25-2011, 12:02 AM
(This post was last modified: 01-25-2011, 12:05 AM by Brightcolours.)
[quote name='BG_Home' timestamp='1295906337' post='5744']
"Center and border sharpness is excellent at any aperture, from wide open down to f/11 (where diffraction begins to reduce resolution)."
I'm a bit puzzled, I have to say. I see this figure - f/11 - in every review of a sharp lens, and also, I see that the resolution starts dropping after f/4 or f/5.6 according to the MTF charts, in every review of a sharp lens. So, my interpretation is that excellent lenses are diffraction limited already by f/5.6 or f/8, not f/11, on 10 MP APS-C. Am I missing something?
[/quote]
Things are not set in stone. Aperture placement for instance influences diffraction softening effects. So, yes, one can see trends regarding diffraction softening. But things can vary from lens design to lens design.
We anyway see the resolution go down slowly from f5.6 or so with this lens anyway, but I am guessing marcus means that after f11 teh resolution really takes a hit from diffraction.
"Center and border sharpness is excellent at any aperture, from wide open down to f/11 (where diffraction begins to reduce resolution)."
I'm a bit puzzled, I have to say. I see this figure - f/11 - in every review of a sharp lens, and also, I see that the resolution starts dropping after f/4 or f/5.6 according to the MTF charts, in every review of a sharp lens. So, my interpretation is that excellent lenses are diffraction limited already by f/5.6 or f/8, not f/11, on 10 MP APS-C. Am I missing something?
[/quote]
Things are not set in stone. Aperture placement for instance influences diffraction softening effects. So, yes, one can see trends regarding diffraction softening. But things can vary from lens design to lens design.
We anyway see the resolution go down slowly from f5.6 or so with this lens anyway, but I am guessing marcus means that after f11 teh resolution really takes a hit from diffraction.