Calumet Shutter Tester for $109

ruben said:
Most of the chances are you may not accept my explanation and perhaps I may discover later I have been too harsh, or impulsive, or over-reacting.
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No offense taken! :)

Two more, slightly technical remarks:

(1) One thing I thought of last night is that Russ Pinchbeck's tester, as opposed to all the other ones I've seen, covers the phototransistor with a sheet of material with a very small hole in it. This is a very good idea. The reason is that the phototransistor's active area usually has a diameter of two to three millimeters. Now if we look at the shutter from a screw mount Leica or Zorki, for example, we notice that it is about 36 millimeters across and has a sync speed of 1/30, meaning that at 1/30 of a second the two curtains are trailing each other with a distance of about 36 millimeters, maybe slightly more. The faster speeds are obtained not by making the curtains move faster, but by moving them with less distance to each other, meaning that a slit is travelling across the frame. At 1/1000 of a second, the slit has a width on the order of magnitude of 1 to 2 millimeters.

If we don't put a small hole in front of the phototransistor, the whole diameter of the phototransistor reacts to light. At 1/30, the curtains are passing by the slit with enough distance from each other that we get a clearly defined "on" signal when the first curtain passes, and an "off" signal at the second. However at 1/1000, the slit is actually only as large as the phototransistor itself or even smaller; so there won't be clear "on" and "off" signals that we need for precise measurements of duration, and instead the signal will look like a smudge where both are smeared into each other. (That's one reason why on many pages you will find a notice that their tester only works reliably down to 1/250 or so.) In order to avoid this, Russ uses what is effectively a small aperture in front of the phototransistor; the hole's diameter is so small that his tester gives precise signals at high speeds. For testing the 1/1250 on a Kiev with its short shutter travel that's probably a necessity... And I that's also why he uses a laser pointer instead of a torch, to get a large amount of light with precise directionality through this very small hole.

(2) in reaction to 40oz:

40oz said:
" if we want to adjust many cameras the easiest thing to do is build two testers with different distances between the phototransistors, one for horizontal and one for vertical shutters."

In my mind, the easiest way to do this would be to arrange the two sensors at opposite corners of the frame, perhaps 40mm apart, so you could use the same device for any 35mm camera, regardless of the shutter orientation/design.
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That would probably work just as well (at least as long as the shutter curtains are parallel to each other, and if they aren't you probably have other problems than shutter speeds...) And it is a lot simpler. In the long run I would like to use some kind of flexible system, because I also have some medium-format cameras, but I haven't really thought of a solution yet.

Philipp
 
It looks like the Calumet shutter testers were a good investment back in 2007. A couple of used ones have just sold on Ebay at $250.

(P.S. I have no prior experience with electronics and managed to build one of the sound card testers mentioned above.)

Rob
 
wow, a lot of stuff to read in this thread, so I haven't read all of it. Take that into account if what I'm about to communicate borders on the absurd. If those smart iPhone developers can make an iPhone into an Ocarina by blowing air into the phone's microphone why couldn't they make a "shutter tester"???
 
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