Copal 0 shutter mount?

[stradibarrius]

What size does the hole in the mounting board need to be for a copal 0 shutter?
I am assuming that the hole has to fit the shutter and not the barrel of the lens?
I have found a lens board for my Calumet cc-400 with a 33mm hole and need to know if a copal 0 shutter will fit this board.

[Gem Singer]

A Copal 0 shutter requires a 35mm opening in the lens board (approx.).

I have a feeling that the person who measured the 33mm opening in the lens board you are getting didn't measure it accurately.

If it's a tight fit for the mounting ring, merely file it out a mm. or two.

[Leigh]

The correct mounting hole diameter for a Copal #0 shutter is 34.8mm.

This is not obvious, because the retainer ring has a lip that fits inside the hole, so the hole is 2.3mm larger than the 32.5mm thread on the shutter.

Here's a view of the retaining ring with lip, from the SK Grimes website:


A Copal #0 shutter would fit in the 33mm diameter hole on your board, but would not mount correctly.

I suspect the hole was cut by someone who didn't know what he was doing and just measured the shutter thread.

- Leigh

[stradibarrius]

I know these are really basic questions but, if for example an advertised lens says"42 mount" does that mean that the lens board should have a 42mm hole in it?

[Leigh]

...if for example an advertised lens says"42 mount" does that mean that the lens board should have a 42mm hole in it?

That's the implication.

However, You have to take the recommendations with a grain of salt, because it depends on the individual making the measurement. You'll see the same Copal #1 shutter listed as 42mm to 45mm. Similarly, you'll see the Copal #0 shutter listed as anywhere from 32mm to 35mm.

Whatever lens you consider, make sure it's in a Copal shutter, then you'll know the correct hole diameter. You can find sizes for other brands on the SK Grimes site www.skgrimes.com and elsewhere, but it's not worth the hassle.

- Leigh

[Gem Singer]

If you are referring to the way KEH describes the previously owned large format lenses, the answer is yes.

A lens with a 42 mount requires a lens board that has a 42mm opening (Copal 1).

[domaz]

If KEH says it is a 42 mount it's probably really a Copal 1 shutter. Or it's a Copal 0 with an external aperture control mechanism that increases the mount size or something like that.