Graflex.org

[bygolly]

I am rebuilding a Crown Grpahic. I can tell that the shutter is running slow but don't know how to figure out how slow it is. Somebody told me that you can test it somehow at 1/60th while holding it up to a fluorescent light. Does anybody know how to do this or know of any other way to check to see if the lens is running at full speed? I don't have the camera with me so and I can't remember which lens is on it, but any tips would help.

[Les]

For many years there would be articles in Pop photo on using a phonograph with a strobe (for stability) to test your shutter. Another way is using a TV
here's a quick article:

http://rick_oleson.tripod.com/index-135.html

I'm not sure about the fluorescent light. I"m sure it's based on the fact that AC is a 60 cycles per second frequency, so a shutter running accurately at 1/60 should capture either a full on or full off cycle, but I can't guarantee it.

Les
_________________
"In order to invent, you need a good imagination and a lot of junk" Thomas Edison

[C. Henry]

60 Hz AC powered metallic vapor arc lights "fire" on both the positive and negative polarity rises in voltage during each cycle giving 120 flashes per second on those types of light. I suspect that the same is true of florescent lights.
I do know that some tachometers used by motor mechanics will read 7200 RPM when pointed at a florescent light. 7200 divided by 60 seconds equals 120 pulses per second.

C. Henry

[glennfromwy]

I would want to test all the speeds, not just 1/60. I use a little Calumet shutter tester. There is a lot of information on the web about using your computer and a sound card to test shutter speeds. That would be a very accurate way to check all the speeds. I just don't know exactly where to tell you to look for this info.
_________________
Glenn

"Wyoming - Where everybody is somebody else's weirdo"

[numnutz]

Here you go instructions and circuit diagram for building a simple shutter speed tester for use with a PC

http://www.davidrichert.com/sound_card_shutter_tester.htm


nn

[Dan Fromm]

Hmm. When I got my Speed I had no idea whether its focal plane shutter was running correctly and no shutter speed tester either.

So I used a known good exposure meter to tell me which aperture was right at a shutter speed and did the equivalent of shooting test strips on Ektachrome. I used reversal film, not negative, because reversal film is more sensitive to exposure errors. Turns out that the FPS was good enough for Ektachrome.

You can always spend a roll of film to test the shutter speeds you're most likely to use, or two rolls to test 'em all and then some. Or you can just assume that the shutter needs and overhaul and have it overhauled.