Copal 1 and Copal 1 Press Shutter sizes

**John Layton** · 23-Feb-2018, 06:58

I have a couple of the polaroid press shutters that I'd like to press (pun intended) into service. I can compensate for the restricted diaphragm opening....but do notice the slight difference tube length, as mentioned above. Would somewhat like Grimes be able to reconfigure this...or might it be more cost effective to simply look for the correct Copal Press shutter? I'll contact Grimes about this also...but am wondering if anyone here has dealt with this issue.

**Dan Fromm** · 23-Feb-2018, 07:45

John, it depends on the lens. I've bought a few GelCam 127/4.7 Tominons for the #1 Copal Press shutters they were in, ended up keeping one as is for general use. Fine lenses.

Anyway, I wanted to put a 210 plasmat type in one of the shutters, was concerned about the ill effects of, IIRC and I don't feel like going upstairs to measure, its 20.2 tube length on the lens performance. I asked my friend Eric Beltrando (visit his site dioptrique.info) what he thought about it. He replied that plasmats aren't particularly sensitive to cell spacing. He thought that increasing the distance between the cells by 0.001 focal lengths wouldn't hurt. He cautioned me that dagor types' performance is more sensitive to cell spacing and that I should put them only in shutters that met the specs.

I'm sure that Adam and Joel can trim the tubes for you. Whether it makes sense economically is an interesting question, depends on how much they'll charge and how much you'll have to pay for shutters that meet the spec.

I've never had to deal with the problem. I accumulated more #0 and #1 press shutters than I needed when Sirchie mug shot cameras sold for less than shipping costs and when a fellow somewhere in NJ sold of a bunch of NOS Prontor Press #1s.

**Corran** · 23-Feb-2018, 08:22

Originally Posted by Dan Fromm

Bryan, yours is a Copal Polaroid shutter. Or Polaroid Copal shutter. They were made for Polaroid GelCams and possibly -- I say possibly because all of the MP-3 shutters I've seen have been Prontor Press shutters with no preview lever and a cable release socket for preview -- the MP-3. They don't all conform to the Compur/Copal/Prontor specification. Typical differences are no preview lever, restricted diaphragm and slightly off tube length. Check yours. Its tube length might be the correct (for #0 and #1) 20 mm. It also might not. My Polaroid #1s' tubes are a bit long and their diaphragms don't open the full 30 mm

Gotcha - I wrongly assumed that since it was a self-cocking Copal, it was a Press. My mistake. Never considered the Polaroid shutters. Not sure on the tube length, I'll have to check another day, but the lens has always performed excellently both close up and at distance so it seems like it is either correct or close enough that it doesn't matter. I'm happy to have it - the self-cocking shutter also helps shooting studio work with multiple flash pops.