Is the white face Copal No 3 actually a 3s?

Hello, I’m looking to adapt m42 lenses to a leaf shutter for a project I’m working on.

I’m currently leaning towards a Copal 3 but they seem hard to come by.

I’ve found some white face Copal 3 shutters but doing research I am confused if they’re actually No 3 or 3S

Does anyone know the front cell thread size on this model and what is a fair price to pay?

Thank you

Copal 3 shutter is probably going to be expensive, if you can find one.

As you probably have figured out, many No. 3S shutters are marked No. 3. I've seen No. 3S shutters in different configurations, so the only way to know is to actually measure the front threads. The No. 3 is 58mm and the No. 3S is 56mm. I have no idea which is generally more expensive, but since you are using M42 lenses, either should work fine -- with an adapter, of course.

I'm pretty sure the white face "Copal 3" I have is a 3S...but I can't get the adapter out to measure the native thread size.

There were apparently two different versions of 3s itself, with two different thread sizes. It's important to take precise thread measurements.

SK Grimes can make a thread adapter for either, or for the later Copal 3 as well, but you'd need to sent the specific shutter to them.

True 3's are tend to be more expensive simply because they're more recent. Often, with the older 3s's, its cheaper to buy an entire older lens with shutter, then simply cannibalize the shutter itself, instead of buying a loose shutter by itself.