Strange COPAL 3

[Greg]

Back to the OP.

I've encountered similar issues, in one case with a modern black Copal 3 shutter. The aperture scale started from f/6.7, and I found out that it was for a Fujinon 250mm f/6.7 lens. I have another Copal 3 or 3S shutter (I forget which), that has the standard thread on the rear, but the front is not the corresponding thread.

Kumar

dito on this end... once bought a #3 Copal shutter with no f/stop scale that had different from standard/normal threads at both ends :-(

[Paul Ewins]

It would certainly appear to be a Copal 3s which had a M56-0.75 internal thread (vs M58-0.75 for regular Copal 3). This is just fractionally larger than the Compound 3 (55.69 x 40 tpi) which would allow manufacturers to continue on with current designs meant for the Compound 3 (which was discontinued in the late 1960s) without the need to design thicker barrels to accomodate a regular Copal 3.

[Leszek Vogt]

Haven't seen albino Copal #3 before. But, I can attest that there is something really screwy with the #3 shutter (in general)....and even SK Grimes mentions that, even if everything indicates "X" is correct, the thread may still not fit. My black Copal #3 would not fit anything standard (rear flange ring), so I ordered a different one from bay and was disappointed again. Had my machinist create one and put an end to this fiasco. Not sure what gives.

Les

[Per Madsen]

Haven't seen albino Copal #3 before. But, I can attest that there is something really screwy with the #3 shutter (in general)....and even SK Grimes mentions that, even if everything indicates "X" is correct, the thread may still not fit. My black Copal #3 would not fit anything standard (rear flange ring), so I ordered a different one from bay and was disappointed again. Had my machinist create one and put an end to this fiasco. Not sure what gives.

Les

It looks like a Copal #3S made to look like the Supermatic shutter design.

[tonyowen]

Just to add another fact. Many items related to optics come with their own peculiar threads. For instance, (relatively) large diameter with fine thread pitches. The thread shape will/can be used to identify a thread type - whitworth, metric, unc etc - But any thread [x diameter y pitch z tpi] used for a particular item/purpose is the correct thread for that application. The other complication is where an imperial thread is identical to a metric thread - eg some BA threads are interchangeable with small metric thread.

Then there are unique thread forms such as pipe, gas, cycle, ad infinitum.

To answer the OP's query, unless there has been an obvious alteration then whatever you have is correct for that item and has to be accommodated.

The arguments about engineers being confused over conversion between metric and imperial dimensions is not relevant and in any case is possible a myth.

regards
Tony

[imagecom]

Haven't seen albino Copal #3 before. But, I can attest that there is something really screwy with the #3 shutter (in general)....and even SK Grimes mentions that, even if everything indicates "X" is correct, the thread may still not fit. My black Copal #3 would not fit anything standard (rear flange ring), so I ordered a different one from bay and was disappointed again. Had my machinist create one and put an end to this fiasco. Not sure what gives.

Les

Leszek,
Thank you for your contribution to the thread. I has gone astray, for sure. I am the original poster and my basic question was, now that I don't know
which lens it belonged to, if I will be able to somehow mount my 300mm Symmar on it, since the original Copal 3 that is on it is busted. Even if I have to find a machinist to make a new thread somehow?

I was thinking that by getting a Copal 3, it would just be a matter of unscrewing a front and rear lens group, and screwing it into the newly acquired shutter. Apparently not. Any suggestions?
Thanks

[imagecom]

Hello,
As an original poster, I am trying to get this thread back on its track.
I measured inside diameter on both sides. Now, I am not an engineer, and what I got on my digital caliper was 55.06mm on both sides.
Posting photos again, couldn't do it with caliper in position because I don't have 3 hands, just two, and one is needed to hold the camera.
This means I am way below the standard Copal 3 size. Any ideas what can be done so that I can mount my Symmar 300mm on it, which has a busted shutter?

[Tin Can]

You asked

Money always works

Try another shutter

Try a friends shutter

Tell us where u r?

[Bob Salomon]

Hello,
As an original poster, I am trying to get this thread back on its track.
I measured inside diameter on both sides. Now, I am not an engineer, and what I got on my digital caliper was 55.06mm on both sides.
Posting photos again, couldn't do it with caliper in position because I don't have 3 hands, just two, and one is needed to hold the camera.
This means I am way below the standard Copal 3 size. Any ideas what can be done so that I can mount my Symmar 300mm on it, which has a busted shutter?

If it were me I would sell it and buy a modern, black version!

[imagecom]

If it were me I would sell it and buy a modern, black version!

Thank you for the suggestion. That would be the easiest way. However, it is not helping.