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I just tested 100mm at f/32 against 50mm at f/16, which have the same entrance pupil size, and when cropped to the same part of the subject, the longer focal le
by CarVac 8y ago
I just tested 100mm at f/32 against 50mm at f/16, which have the same entrance pupil size, and when cropped to the same part of the subject, the longer focal length simply wipes the floor with the shorter focal length.
https://i.imgur.com/GtljNmg.png https://i.imgur.com/GtljNmg.png top is 50mm, bottom is 100mm
Why? The antialiasing filter and demosaicing destroy detail at a fixed scale relative to the captured image.
- BeetleB 8y agoWow - Thanks for actually making the effort. A few quibbles: 1. The goal is to maintain the DOF distance. For 100mm at f/32, if you go to 50mm, you need f/8. 2. The assumption is that the lens is as sharp at 100mm as it is at 50mm (on some lenses this is a terrible assumption). I tried a similar experiment comparing 25mm with 50mm (f/5.6 vs f/22). You can see the results at https://imgur.com/a/ik6qe5K https://imgur.com/a/ik6qe5K To me, they are almost identical - with 25mm seeming a tad bit sharper. In a way, though, you're right - the difference is so small that I might as well shoot at f/22.
- CarVac 8y agoThe goal is to maintain DOF and field of view; if you crop to the same field of view, and the entrance pupils are the same size, then you have the same DOF. 100mm at f/32 is the same as 50mm at f/8 only if you don't crop 50mm by 2x. These are both excellent lenses, and at f/32 and f/16, optical quality basically ceases to matter.