Copal Shutters Interchangeable?

[salfavata]

I have a chance to purchase a used 90mm Super Angulon f8 (Linhof variant) here in France, and it has a Copal 0 shutter in the latest all-black version. However, the aperture scale on the shutter extends to 5.6, and the aperture mechanism does indeed open to 5.6. but no longer reveals the seven-sided polygonal shape from the aperture blades.

There is a Rodenstock quality seal on the shutter so it is not the original.

Questions: 1. on two different focal length lenses with different aperture ranges, could the Copal 0 shutter be interchanged with the other lens without exposure issues? 2. Or are somehow the apertures at each f-stop appropriate for a particular focal length lens?

Lens is in beautiful condition, no Schneideritis. Thanks.

[Dan Fromm]

Oh, dear, another instance of the question that won't die.

Aperture scales are lens specific. A good repairman -- in the US, SKGrimes, for example -- will have the pre-made aperture scale you need or, if necessary, can engrave a scale on the shutter. For you, Gerard Metrot in Paris comes to mind, but I'm not sure he's still working and don't have his contact information. Ask on galerie-photo.info

[Lachlan 717]

The scales are interchangeable along with the lens elements.

Two screws hold the scale in place. The markings relate to where the aperture knob movement brings the blades into the path of the light through the lens.

This will be at a different spot for different lenses.

[Bob Salomon]

Just as important the lens may or may not require shims for proper spacing between the front and rear groups. If someone just switched shutters you will probably find that there is also a shim issue. That would effect performance!

[pepeguitarra]

My experience with the all-black (the latest) copal has not been good, they are the ones with the speed going off most of the time. The old ones behave better in my case. I have not seen any problem moving from one Copal to another Copal equivalente. Three of my lenses have scales on white paper I glued on to them. I learned to calculate the scale from the book: Using the View Camera by Steve Simmons. You can get the book in Amazon for less than $15, or new (I think they still sell it), it is the best book on LF.

[salfavata]

Ahh. I see that I didn't do a good job explaining myself. It's not about physically replacing the scale itself, but related to exposure.

In other words, if my meter says f16, and I set the aperture at f16 on this lens, could the exposure potentially be off because this Copal 0 came from a lens with a wider aperture range, and/or perhaps a different focal length?

I've been doing LF for 40 years, this never occurred to me. If I were in the U.S., be a no brainer... just test some film. But things are a bit more challenging here, and LF film/processing is expensive. Thoughts?

[Bob Salomon]

Ahh. I see that I didn't do a good job explaining myself. It's not about physically replacing the scale itself, but related to exposure.

In other words, if my meter says f16, and I set the aperture at f16 on this lens, could the exposure potentially be off because this Copal 0 came from a lens with a wider aperture range, and/or perhaps a different focal length?

I've been doing LF for 40 years, this never occurred to me. If I were in the U.S., be a no brainer... just test some film. But things are a bit more challenging here, and LF film/processing is expensive. Thoughts?

Yes, it will. You need the proper scales.

[Leigh]

In other words, if my meter says f16, and I set the aperture at f16 on this lens, could the exposure potentially be off because this Copal 0 came from a lens with a wider aperture range, and/or perhaps a different focal length?

The aperture is actually defined as a fraction of the focal length, written either as f/n or f:n.

These mean the aperture diameter equals the focal length 'f' divided by f-number 'n'.

Theoretically, if you change the cells on a shutter to those of a different lens WITH THE SAME FOCAL LENGTH, the aperture scale will be reasonably close. If the new lens has a different focal length, the scales will be WAY off.

- Leigh

[salfavata]

I thought the exposure would be off, but math is definitely not my forte. Thanks for the help!

[B.S.Kumar]

https://www.largeformatphotography.i...Aperture-Scale

Kumar