I got a Calumet shutter test, just testing a few shutters.
I found between 1 and 1/60 most reading are within 1/6 stop but when I hit 1/250, or 1/400 the reading is way off. Is that because of the shutter or the shutter tester?
I got a Calumet shutter test, just testing a few shutters.
I found between 1 and 1/60 most reading are within 1/6 stop but when I hit 1/250, or 1/400 the reading is way off. Is that because of the shutter or the shutter tester?
A shutter is accurate if it is ±30% of the marked speed. Except for a shutter like the Rollei Linear Motor electronic shutters most mecanical shutters: Compur, Copal, Prontor, Seiko, will be may be more then ±30% at their fastest speed. This is true for these shutters regardless of the format used. In other words, a Hasselblad Prontor shuttered lens will be quite a bit off of a true 1/500.
If I shoot @ 1/500 I may have very good chance to have under/over expose my slides, is that right?
BTW, I remember shooting 35mm format, there is a rule of thumb that if you hand held a camera the shutter speed should at least the inverse of the focal length of the lens. Does that hold for LF hand held cameras?
Keep in mind that most leaf shutters will measure significantly slower than their "effective" speed even when they are in adjustment. A 1/500 shutter can be expected to measure 1/400 or less when tested with a shutter tester--this does not mean it is 'running slow' because it takes a finite amount of time for the leafs to fully open and close. This is compensated for with a slighly longer open-time. With leaf shutters at high speeds, shutter speed is also a function of aperture.
Kentucky windage.
I've had very good luck with the Calumet tester, both for large format lenses and small
cameras. The readings reflect real world film testing. Every single Copal shutter I've
tested, new or old, was way off at the highest speeds. But I've had Compur shutters
which were spot on, even for analagous focal lengths, but otherwise hated because of
their higher vibration. I came to the conclusion that most of this is in fact due to the
respective shutter designs. Almost no one uses the higher speeds with a view camera
anyway, and if they do, a strobe is probably involved and will be the primary determinant of the exposure anyway. I carry a tally of all my shutters, and would
consider anything a third stop off to be of consequence with color tranny film. About
once a year I retest each lens I frequently use. They don't seem to vary much with
age.
Are you using the Calumet instructions, especially important for the higher shutter speeds?
--
Alan
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