Shutter Swap for Schneider Symmar

[Fragomeni]

Hi all. I have a Schneider Symmar 210mm convertable lens originally set in a Synchro-Compur shutter. The Synchro-Compur is shot and is probably not repairable. I spoke with S.K. Grimes yesterday and they said that the lens elements fit straight into a Copal 1 shutter. I spoke to them about purchasing a shutter and having them etch a new aperture scale but the time frame is cutting it a little too close for when I'll need to be using the lens. I ended up finding an unused spare Copal 1 shutter in one of my drawers that I'd forgotten about. The elements screw in just as S.K. Grimes said. They did not mention needing shims or anything and said that the elements go right into a Copal 1 which seems to indeed be the case. My last concern is the aperture scale. My question is, can I remove the aperture scale from the original Synchro-Compur shutter and fit it to the new Copal 1? All dimensions and openings appear to match between the two so I would assume that as long as I line up the scale properly in relation to the Copal 1's max opening it should work. Can I do this? Also, I found this post describing a fairly simple way of making a new scale if I need to go that route. Any help would be appreciated. I'd like to take care of it here rather then having to send it out because of my schedule. Thanks!

[Kevin Crisp]

You should be able to swap the lens over to the new shutter with no problems at all. You shouldn't need shims.

On your second question, and without the benefit of having a Compur in front of me, don't the aperture numbers on the scale bunch up as the aperture gets smaller? Whereas the Copal is linear and evenly spaced? If so, then using the same scale won't work.

On the other hand, you can set the old shutter at f:16, for example, and mark f:16 on the copal by comparing the two apertures. The relative crudeness of the opening on the Copal will make some estimation necessary, but this can be done. When you have time, Grimes can make you are proper scale for the Copal. Obviously with a meter on the ground glass you could check your estimations if you have any doubt. Good luck. A convertible Symmar can be a terrific lens.

[Fragomeni]

Indeed the numbers do bunch up on the Synchro-Compus. I didn't think about one being linear and the other not. Looks like I'll need to make the scales for the Copal (or eventually have Grimes make some for me). Thank you for your help Kevin!

[Kevin Crisp]

Seriously, you can eye ball them and make a decent temporary scale. Use the white tape from a P-Touch labeler, write on it with a Sharpie, and you're good to go. I've done this several times and many years later I'm still using my temporary scales.

[Fragomeni]

The lable tape is a great idea. I was wondering what I'd use.

[Leigh]

You shouldn't need shims.

This cannot be determined until the cells are mounted on the shutter and the assembly checked on a precision collimator.

All manufactured products have tolerances. If the shutter length is a tad shorter than the cells need, you must add shims.

Granted, that doesn't happen very often.

- Leigh

[Kevin Crisp]

I've done this maybe 6 times or more on convertible symmars, and checked with my caliper that is good to 0.001 inches, which I think is precise enough to measure a tad, and every one has been right on the money.

If you want to pay somebody to check your work, go for it. I think it will be fine without that.

[Leigh]

...and checked with my caliper that is good to 0.001 inches, which I think is precise enough to measure a tad, and every one has been right on the money.

Even if your shutters are all exactly the same dimension, it doesn't tell you what spacing the cells of a particular pair require for optimum focus.

I can measure shutter lengths to ±50 millionths of an inch. That still doesn't tell me what spacing the cells want.

It all comes down to what level of precision is required for the application.

- Leigh

[Fragomeni]

Yea, when I spoke with S.K. Grimes I asked if anything needed to be machined. He said no machining was necessary and that they simply screw it into a new Copal 1 and make new aperture scales and thats it. He looked at his spec sheet for the specific lens and clarified this for me so I think I'm safe not worrying about shims.

It all comes down to what level of precision is required for the application.

When it comes down to it that is exactly right.

[Kevin Crisp]

This forum has a great capacity for overcomplicating things. Just do it and go make some photographs.