 Mario toni Belamaric |
Accuracy of shutter speeds on analog cameras Is it true that after a while shutter speeds on analog cameras are no longer accurate? For instance, 125 is no longer 125 but some lower or higher speed.
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Jon Close |
Depends on the specific camera, and how long is "after a while." Older models with mechanically timed shutters may lose some accuracy with wear, but generally not enough to materially affect exposures unless it's actually damaged or gummed up with dried/bad lubricant. Except for the most critical scientific work, differences of up to 10% (less than 1/6 stop) are immaterial with respect to exposure. I doubt that electronically timed shutters used on modern SLRs change at all. Digital SLRs use the same shutter system as analog SLRs.
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Mario toni Belamaric |
Yes Jon, I have EOS 3, so I suppose, since it`s a modern SLR it is highly unlikely that shutter speeds will change!
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Peter K. Burian |
Mario: Most current SLR cameras' shutter speeds are extremely accurate. Perhaps you are thinking of this. In Program mode, the camera may show that the settings are f/8 at 1/250 sec. The camera may actually be setting f/7.8 at 1/240 sec. for the most accurate exposure. (Or some other combination that does not follow the familiar aperture/shutter speed steps.) Old mechanical cameras could not do that. Cheers! Peter Burian
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John A. Lind |
Not entirely true . . . a well designed and reasonably cared for mechanical shutter . . . including not leaving it on a closet shelf unused for a decade . . . can retain amazing accuracy. What Jon hinted at with gumming is typically caused by not exercising the shutter for many years . . . grandpa's old camera sitting on the hall closet shelf or worse yet . . . in a box in the basement or attic . . . for 10-15 years. While it's true that entirely mechanical cameras typcially have one-stop increments in shutter speed, exposure accuracy is allowed by using mid-stop aperture settings. I have a 50 year old RF that has no detents on lens aperture with fairily wide spacing between aperture settings that allows estimating to about 1/6th stop apertures. I have another RF, designed about 40 years ago that has aperture detents at 1/3rd stop increments allowing +/- 1/6th stop accuracy . . . and I shoot chromes through both . . . notorious for demanding exposure accuracy (typically one sets it for mid-tone) without any problem. The latter one has been in use by me for about 25 years with zero overhaul. Both the 1/2-second and 1/500th shutter speeds . . . where loss of accuracy typically occurs first . . . are still dead on (had them tested recently). -- John Lind
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