02-27-2012, 09:41 AM
(This post was last modified: 02-27-2012, 09:46 AM by Brightcolours.)
Those are nonsensical figures. The lens is an f4 lens, and the f4 aperture will limit any lens to 373 lp/mm, due to diffraction. And that is for MTF-9. Or 173 lp/mm for MTF-50.
And that would be for f4, but we see that the lens wide open does not perform that well at all. We see that resolution improves at f5.6, where the maximum resolution will be 266 (MTF-9) or 123 (MTF-50) LP/mm.
So even though this lens can not reach more than 266 LP/mm or 123 LP/mm (which it does not even), that formula gives you resolutions only possible at f1...
Like I have said before, the best SLR lenses reach MTF-50 resolution figures between 100 and 200 lp/mm, lenses performing better will have to show higher test scores for f2.8 for instance than for f4 or f5.6.
And that would be for f4, but we see that the lens wide open does not perform that well at all. We see that resolution improves at f5.6, where the maximum resolution will be 266 (MTF-9) or 123 (MTF-50) LP/mm.
So even though this lens can not reach more than 266 LP/mm or 123 LP/mm (which it does not even), that formula gives you resolutions only possible at f1...
Like I have said before, the best SLR lenses reach MTF-50 resolution figures between 100 and 200 lp/mm, lenses performing better will have to show higher test scores for f2.8 for instance than for f4 or f5.6.