Electronic Shuttersgreenspun.com : LUSENET : Large format photography : One Thread
How consistent are electronic shutters? Does anyone have experience with this? Also, how accurate are they, that is, do they hit the actual stated time?
Is anyone familiar with the Melles Griot 04 shutters that I see on EBay occassionally? Does the 04 size correspond to a Copal 0 or 1?
I'm asking, because I would like to find a shutter that's very consistent, giving the same exposure everytime. Best would be a shutter in the Copal 1 size. But, a Copal 0 size would also be OK.
-- neil poulsen (firstname.lastname@example.org), November 22, 2001
The Melles Griot 4 Shutters are the same size as an Ilex 4. In fact, Melles Griot acquired Ilex and continued to produce their mechanical shutters for awhile. While the electronic shutters seem like a good solution to the problem of speed consistency, they do require a control box and power. This may not be the most convenient thing to do in the field. Copal and Compur shutters, while not as accurate as their speed scales indicate, can be pretty consistent if in good working order. What I suggest is that you invest in $79 electronic shutter checker and test what you have. If the shutter fires at the same speed say, 3 times in a row after exercising it a couple of times, what more could you want? Just make a little label that you can stick to the lens board with the adjusted speeds written on it (generally the speeds below 1/50 will be a bit fast and the the speeds above, a bit slow) and follow that scale. If you test your shutters once a year or before you embark on an expensive journey, you should be able to produce remarkably consistent results with mechanical shutters. If you're ambitious, you can get a number of barrel lenses that, with a custom adapter, will screw into one shutter! Now you can test that shutter and use it with three or more focal lengths. You can check out Steve Grimes' site for more details about how this is done. Good luck.
-- Robert A. Zeichner (email@example.com), November 22, 2001.
I have to agree with Rob... new copal shutters are amazingly accurate. I have tested my 10 LF lenses all with copal shutters, not only were they all within +/-2% of the stated shutter speed, they were amazingly consistent between firings. About 1%. If you are having problems with a shutters consistently, you may be looking too far for a fix. Unless you have something else in mind.
-- Bill Glickman (firstname.lastname@example.org), November 22, 2001.
No leaf shutter is going to be absolutely accurate. Whether mechanically or electronically timed, leaf shutters all have a finite opening and closing time, and this changes the efficiency of the shutter depending on the particualr f stop and shutter speed. Even if the timing was absolutely accurate and consistent; in order to get exposure accuracies closer than plus or minus a few percent, you'd have to calibrate the shutter at every speed to get an aperture versus effective time curve. A normal shutter speed tester won't do that, because it just looks at the length of time that the light is above a certain threshold.
You'd need to use either a lot of film, or an instrument that integrates time and intensity. (An exposometer? I don't know if anyone makes such an instrument.)
For normal pictorial photography, it ain't worth the hassle. Just have your Copals checked over ocassionally.
-- Pete Andrews (email@example.com), November 23, 2001.
Good point Pete! I never considered checking the shutter speeds at every apt. My results above were achieved using a working apt., like f22.
-- Bill Glickman (firstname.lastname@example.org), November 23, 2001.