Copal 3

[luis a de santos]

Could somebody tell me the exact thread size for the Copal 3?
I need to place a filter in front to protect the blades since I only have a cell in the back for this lens I am using.

Thank you very much

Luis

[Peter K]

Could somebody tell me the exact thread size for the Copal 3?

M 58 x 0.75mm

If it's M 56 x 0.75 your shutter is a Copal 3s.

[luis a de santos]

Thanks .
How do I tell if it is the S variety or not?
Sorry for my ignorance.

Luis

[BrianShaw]

The best way to tell the difference, luis, is to measure; the S is 3 mm smaller.

[Øyvind:D]

In my experience, a filter will not fit, as the threads starts to deep, neither on 3 or 3S. Here is one drawing of 3S
http://www.skgrimes.com/products/

[ic-racer]

You could try putting the cell on the front and see if you notice any difference when stopped down.