Re: Leaf shutters I did a series of shutter speed tests on both focal plane and leaf shutters, not measuring the light levels, just the speeds. Unfortunately the results are buried deep in my piles of notes, but the gist of it was that.. Leaf shutters were interesting. Set one to 100th of a second and measure the time the shutter was open at the centre and at the edge - the centre may have been open for 1/80th of a second, but the edges often recorded times of 1/125th - 1/500th of a second But this means nothing really as the shutters are well designed to average it all out and give a net exposure that is correct, or, as Andy suggested you can treat the different exposure values across the film plane as being averaged out. Uneven illumination across the film plane is more a result of the lens characteristics and the interaction with the iris. Often wide angles yield less light at the corners, but also as anyone who has played with various lenses on differing formats will know, the size of the image circle has it's effects. Get the format to exceed to the size of the image circle the lens is capable of and you'll get vignetting, but simply get close to that and you'll get falloff. Some lenses actually brighten the centre too! Roger asks Not wanting to prolong this thread, but what effect does the number of leaves have? the more they have, the closer to a circle the shutter gets, that's about it. Same with the iris. Were you to use a sickle shaped iris, your out of focus highlights would be sickle shaped ;) k
