View Full Version : Calibration of Copal Shutters

Spencer Ladd
2-Dec-2010, 21:43
What is the best way to calibrate my copal shutters? I have small differences between each one... bellow extension has been calculated.

Can I do it myself, affordably, or do I need to take the lenses to a shop?

Frank Petronio
2-Dec-2010, 21:49
Are you talking about 50% different or 10% different? They aren't going to be that precise but maybe a good service tech could get them all to be within 20% of each other.

Spencer Ladd
2-Dec-2010, 22:26
50%? 1/2 stop?

Frank Petronio
2-Dec-2010, 23:32
I'd send them off for a CLA, they should be able to get them to within 20% of the stated speeds I believe.

As for DIY, that's beyond me.

3-Dec-2010, 07:26
50%? 1/2 stop?

50% longer is a half a stop. 50% shorter is a whole stop.

These shutters were never designed to be more precise than about a quarter stop--that's probably the limit for mechanical shutters in actual use.

Rick "who measures and corrects" Denney

3-Dec-2010, 07:31
You can adjust the mechanism, but you can be there all day going back and forth for just one shutter. I must have 50 shutters at least, so sometimes that is not practical.

If you have access to a shutter tester, then just make a note of the actual shutter speed of each shutter and use that number, rather than the marked number.

Easiest DIY approach is to do some Zone I frames at your few favorite shutter speeds. If they frames deviate from 0.1 then the shutter speed is off. With some trial and error you can figure the actual shutter speeds to 1/2 or 1/3 of a stop.

What?? you don't have a densitometer?? (Pet Peeve: how can one spend $400 on a spot meter and not own a $100 densitometer??? :) )

Bob Salomon
3-Dec-2010, 08:22
factory spec is 30%. Are yours farther out then that?

John Koehrer
3-Dec-2010, 16:08
Agree with Mr Salomon.
Perfection isn't in the cards for your shutters. If your frames deviate by .1 your living on a different world.
Test them, determine the deviation & go from there.

Spencer Ladd
3-Dec-2010, 20:10
I'd send them off for a CLA, they should be able to get them to within 20% of the stated speeds I believe.

As for DIY, that's beyond me.
CLA stands for what? I don't think I can do this own my own, I do not have a densitometer or a shutter tester.

I have one lens farther out than 30%, I bought it used.

Thanks for all the help.

Spencer Ladd
3-Dec-2010, 20:28
So where do you get a good clean, lube, adjust? I live in Boston, MA. I will ship the shutter if needed.

Frank Petronio
3-Dec-2010, 20:30
Frank Marshman
Camera Wiz
169 Pleasant Hill Rd
Harrisonburg, VA 22801
(540) 434-8133

He's good and not too expensive either. I'm sure there must be someone closer but I don't know who.

Spencer Ladd
3-Dec-2010, 20:39

Doremus Scudder
4-Dec-2010, 04:04

This thread is duplicated. Since there are valuable responses in both threads, would it be possible to merge them?


Doremus Scudder

Spencer Ladd
4-Dec-2010, 14:25
Yes. Please let me know how and I will.

4-Dec-2010, 14:51
See the other thread for my suggestion to you. BTW, I now know where you live. Hello "beantown"; I was once a Bostonian and miss it every day!

Peter Lewitt
4-Dec-2010, 20:49
Hi Spencer

Sent you a PM