Quote Originally Posted by Alan


Thus, would a MLU with 1/500 sec on a tripod be a significant improvement for a still shot, vs hand held, in terms of sharpness?


I'm thinking it wouldn't. Sure, intrinsically, the mirror slap will induce vibrations, but will it significantly affect image sharpness?


Significantly? I suspect not. Technically, it will affect it to some extent, probably non-linearly depending on the frequencies of the vibration relative to the shutter speed. But the effect may not be detectable in the final image with high shutter speeds, or with very long exposures. I'd guess (and it's completely a guess) that mirror slap would affect the image most with exposures in the 1/100 - 1 second range, and yes, focal length will matter (because the smaller the angle of view, the more sensitive to vibration).


I can tell you that vibrations can affect image sharpness even at high 'shutter speeds' - not based on experience with camera optics, but microscopy. Even with exposures of 2 milliseconds (= 1/500 s) in digital microscopy, the vibration inherent in buildings (HVAC, plumbing, etc.) that we humans can't perceive causes loss of sharpness (in this situation, there's nothing else moving in the optical system - the 'shutter' is electronic). For that reason, my microscopes are on air tables (metal-clad slabs of granite/marble weighing a few hundred pounds, floating on a cushion of nitrogen gas). Just a little more stable than your average tripod. []


But, that's a different application than shooting with a dSLR. In the 'real world' I'd suspect that a fast shutter speed will overcome most of the vibration issue, if not all. I guess my philosophy is that if I'm going to take the effort to set up a tripod and use a cable release or timer, I might as well use MLU as well. If I'm trying to shoot someone or some creature moving around, timing the shot is more important, so that precludes using MLU.