Shutter Testinggreenspun.com : LUSENET : Large format photography : One Thread
I was just reading a book "Creative Black and White Photography" by Bernhard J. Suess and he mentioned testing shutters for accuracy and intimated that this was a valuable thing to do. He suggested a "portable shutter tester" from Calumet.
My question is: Is shutter testing something that is valuable to do? I have three new Schneider lenses in copal shutters. Is the device that he mentions valuable or does one use a local lab for testing? This was not even on my radar screen before I read this. Should I pay attention?
Thanks as always!
-- Scott Jones (firstname.lastname@example.org), February 04, 2002
Scott: A healthy person can read a medical dictionary about all the things that can go wrong and eventually start to feel a little sick. It's kind of like that. Your Copal shutters are probably all working just fine and will continue to do so for decades. They are EXTREMELY reliable. You can buy inexpensive digital timers for shutters, and they work pretty well on the slow speeds. Once you get above about 1/60th or 1/125th (speeds you're probably never going to use anyway) they always say your shutter is running slow. (Either because it is or because you need a much more expensive and sophisticated meter to take into account the effective time the shutter is fully open after you discount for time spent opening and closing.) If you like buying older shutters in various stages of neglect or disrepair, one of those gadgets is kind of handy, within its limitations. For what you have, I'd say you don't need it and you probably never will. When you are out there using those fine lenses, listen to the sound of the shutter at the speeds you use the most. If you pay attention, a significant error in the slower speeds will become very obvious to you by the time it finally happens, if ever. You'll know something is wrong.
-- Kevin Crisp (KRCrisp@aol.com), February 04, 2002.
Hi Scott, the previous post is full of good advice. You'll probably ever need one. Also, you can shutter test - kind of - by taking a series of negs at progressive shutter speeds and observing the change in density of your negs. I mean if your shutter is off, you won't see a nice one stop change in density. That said, I can recommend the Camulet shutter tester; I have one and I think it's great. Once you test them, you know exactly where you are on all your shutters, and you can retest them anytime you want, and you can own the instrument for what it would cost you to have them tested. Also, you can test the lens on camera if you want to be picky. Good luck, David
-- david clark (email@example.com), February 04, 2002.
Probably not an issue on top-notch contemporary lenses like the ones you've mentioned, I agree, but those of us using some of the many fine older lenses out there wouldn't want to go too long without some sort of shutter test--whether of the do-it-yourself variety, or the sort performed by experts who can actually repair slow shutters, or tell us how far off they may be. It's an argument for barrel lenses, I suppose, but if you're calibrating equipment for zone system work, this seems an essential step. Even new shutters do vary somewhat.
-- Stephen Longmire (firstname.lastname@example.org), February 04, 2002.
Thanks this was all really helpful...
-- Scott Jones (email@example.com), February 05, 2002.
I just received the Calumet shutter, and I'm pleased with my purchase. I built a neat jig for it to hold the lens, the shutter tester, and a light bulb, all positioned on axis to obtain the best results.
I've checked a few of my lenses, and some aren't as consistent as others. For example, I've decided to use my 150mm lens for calibrations versus my 180mm. Most of my lenses have Copal shutters, and I notice that they all seem to be within +/- 5%, which is good.
Having read the comment in this post regarding the accuracy of my tester for speeds less than 1/60th of a second, I'm going to compare my tester's accuracy against the data provided by my local repair store.
-- neil poulsen (firstname.lastname@example.org), February 05, 2002.
Scott: I'm a little disconcerted that a book with the word 'creative' in the title then proceeds to get its readers anal about shutter speeds.
Some of the books that I've picked up in the past that use words like 'creative' or 'perfect' in the title, have been illustrated with the most uninspiring, badly printed and mundane pictures I've ever seen. I wonder why that is?
-- Pete Andrews (email@example.com), February 05, 2002.
Neil - one thing to remember is to test at a "taking" aperture. Whenever I had my shutters calibrated outside I always insisted on having them tested @f/22. Now that I test my own I continue to do the same. It does no good to test a shutter at f/4.5 when the actual aperture in use will be much smaller. The time lost in opening to a larger aperture and then closing again will make the "apparent" shutter speed faster for larger apertures. A shutter that will test to 1/500 at f/4.5 will be a up to a half stop or more slower at f/22. This will be proportionate to the mass of the shutter blades, the forces applied, and the "dwell" (fully open) time. Among modern shutters of which I'm aware the forces of acceleration are the same for 1/2 sec. or 1/400 (this wasn't true for some older shutters), and the mass is a constant, thus the speed of the blades is a constant - only the dwell time varies. Along with this it is critical to use the minimum amount of illumination to trigger the timer - too high and it will still read with the shutter partially closed/open (much less of a problem with smaller apertures) and give slow readings. Don't be surprised if your 1/500 actually reads 1/325 at f/22. Granted that this is "nit-picking" to most people, but it's something to keep in mind. It's also why you'll never see 1/500 on a #4 or #5 shutter - the stress would be enormous.
-- Wayne DeWitt (firstname.lastname@example.org), February 06, 2002.
In the past I tested shutters, when needed, with a phototransistor circuit and an oscilloscope. This worked very well even at the highest speeds a leaf shutter is capable of. I was going to check out a used shutter I bought recently but have had a hard time finding a phototransistor. Radio Shack and places like that don't seem to have these anymore. Anyone have a suggestion.
-- Dave Schneider (email@example.com), February 06, 2002.
-- Wayne DeWitt (firstname.lastname@example.org), February 07, 2002.
Dave, Buy any of the later Oscilloscope cameras that show up on ebay and you'll find photo transisters. Usually 2 in each. C59 rings a bell. I hope this is correct. They were part of the more complex cameras light measuring system for exposure. The older and simpler ones don't have them.
-- Jim Galli (email@example.com), February 07, 2002.
I found a quick way to do a shutter test when I got impatient one weekend after rebuilding the rear shutter of my Graflex.
A TV set, a dark room, and a polaroid back can give you an idea of how your shutter is firing.
Turn the contrast on the TV to max, and take a close, sharp-focused shot of some part of the screen using the polaroid back. Take a loupe to the picture and count the number of scan lines that appear. Then multiply this by the scan time (77microsec/line?) to find out how long the shutter was open. If you are using a travelling-slit shutter, make sure the axis of the slit is running across vertically.
Good luck, Tox
-- Tox Gunn (firstname.lastname@example.org), February 13, 2002.