Malfunctioning No. 4 Acme Synchro Shutter

[Ethan]

Hey everyone,

I was hiking up a mountain to take some photos today. Ended up not getting many, due to mist obscuring most views, but with the few that I did take, I noticed that the shutter on my lens has begun malfunctioning.

Here's the issue, which I don't understand, but maybe some of you will, and might be able to help me determine if it is worth trying to get it fixed. On shutter speeds 1/5, and 1/10, the shutter gets stuck open. I don't really understand this, because at speeds higher and lower than that, it seems to work fine. on the slower speeds, it might be firing a little slow, but it's hard for me to judge that without a shutter tester.

One theory I had, is because it was cold on the mountain, the lubricants might have gummed up and made the shutter blades sticky, but in my (limited) knowledge, that wouldn't explain why it still works at even slower speeds, and it also still didn't work after it warmed up.

Do any of you know what may be the issue, and whether it is worth fixing? I know these old shutters are only getting harder to find, but the lens (and old Eastman Ektar 12") isn't in great condition, so I may be better off just buying a new lens. Any ideas?

Thanks,
Ethan

[Kevin Crisp]

Sounds like you need a basic CLA. My experience with Acmes in this size is that they can go 10+ years before needing service and they are reasonably accurate. If the lens and working shutter aren't worth the $100 or so it would cost to fix it, then don't. I like them for old shutters and have built protar sets around them because of their relatively large opening and general reliability.