| Author | Message | ||
     rick oleson Rating: N/A |
tony's right.... accurately measuring the fastest speeds of a leaf shutter is pretty futile, since even a perfectly accurate one will give a different speed at every aperture. the really right way to test one would be to plot the intensity over time on an oscilloscope and take the area under the curve, but even doing this the aperture variability remains. i have one of those cheaper shutter testers, and the prescribed method is to set it up with the light intensity adjusted to trigger the tester as the shutter passes the half-open point. this is easier said than done, and i have not gotten consistent readings trying to do this with a leaf shutter. you can sort of see the problem graphically if you try to evaluate a leaf shutter using a CRT screen as described on my website: with a focal plane shutter in good trim you get a line whose width is proportional to the speed... with a leaf shutter (viewed through the lens) the line bulges, representing different effective speeds in different portions of the lens area (faster at the edges and slower in the center). |