http://personal-view.com/talks/discussions/tagged/stopping/p1/feed.rss Sat, 02 Nov 24 21:29:37 +0000 Tagged with stopping - Personal View Talks en-CA http://personal-view.com/talks/discussion/1467/sharpness-and-aperture Wed, 16 Nov 2011 05:26:50 +0000 Vitaliy_Kiselev 1467@/talks/discussions
Let’s look at a very good wide-aperture prime, the Canon 35mm f/1.4 “L” lens. Here are the Imatest results for fifteen Canon 35mn f1/.4 lenses measured at both f/1.4 and f/2.8 apertures. (The number on the vertical axis is the MTF 50 weighted average for the entire lens, that on the horizontal axis is MTF50 at the center point).



More lenses compared:


Small conclusion:
1.Some lenses benefit greatly from being stopped down, others very little.
2.For those lenses that do benefit, stopping down just to f/2.0 provides the majority of resolution improvement. The difference between wide open and f/2.0 is generally much greater than the difference between f/2.0 and the maximum resolution.
3. Getting the edges and corners sharp requires stopping down to at least f/4 for most wide-aperture primes, and some really need f/5.6. Stopping down to f/2.8 may maximize center sharpness but often makes only a slight difference in the corners, at least on a full-frame camera.
4. None of the lenses performed any better after f/5.6 (for the center) or f/8 for the corners. Most were clearly getting softer at f/11.

Read full article at: http://www.lensrentals.com/blog/2011/11/stop-it-down-just-a-bit

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