Quote Originally Posted by Tony Printezis


In my attempts I found that IQ drops noticeably if I go that narrow. I use XTi/40D and I've experimented with a few of my lenses...
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Tony,


I have used my XTi with F16 for a good number of times and I barely found any image degression. I will use F11 or narrower to get great DOF or I need to push for long time exposure. If you're shooting night scenes with long time exposure, first make sure that your camera is supported steadily and you use a remote controller or cable release. I found myself not getting sharp enough shots because of slight camera shaking (some time it'sdue tothe wind). The diffraction (regarding XTi at least) should not be a concern at F16 in my opinion.


Ben