Archived posting to the Leica Users Group, 2001/04/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 04:10 PM 4/17/2001 -0400, Austin Franklin wrote: > >Certainly. It is part and parcel of a leaf shutter design. The leaf >shutter blades have to travel from the center to the edge, therefore, the >center will be open for a longer period of time, and that time decreases >toward the edges. With small apertures, the time it takes for the shutter >to travel the distance until it's 'fully open', which is when it's past the >aperture blades, is very small. Contrast this with the distance it has to >travel until it's 'fully open' when the aperture is wide open. The times >are different, though the shutter speed is the same. This amount of shutter >blade travel time becomes significant when that amount of time approaches >the shutter speed time. I have been most reluctant to post to this thread due to the vitriol it has generated. However, at the risk of calumnies of all sorts dumped on my head, allow me to point out the historical truth that Voigtlander did great work on electronic shutters in the early 1960's which allowed these to be remarkably accurate -- I believe their leaf-shutter designs were consistent to more than 99% (meaning that an indicated 1/500" would actually be between 1/495" and 1/505") by 1963. Several Japanese firms were working in the same area of research then or shortly afterward. A mechanical leaf-shutter design will have, as Austin indicates, some problems with accuracy, though less than the error in a focal-plane shutter. But either an electronically-assisted shutter or a pure electronic shutter will be immensely accurate. None of this matters in our current world, of course, where even chromes are good for 1/3 of a stop up or down. Marc msmall@roanoke.infi.net FAX: +540/343-7315 Cha robh bas fir gun ghras fir!