Copal 3 shutters

[colrehogan]

I was out shooting last weekend and was going to switch a board that I had used with a Copal 3 shutter with silver ring to a lens with a Copal 3 shutter with black ring and found that they were different. The black ring shutter threads seemed to be just slightly larger than the silver ring shutter threads. Is this normal? Both shutters are labeled as Copal 3.

[coriana6jp]

I was out shooting last weekend and was going to switch a board that I had used with a Copal 3 shutter with silver ring to a lens with a Copal 3 shutter with black ring and found that they were different. The black ring shutter threads seemed to be just slightly larger than the silver ring shutter threads. Is this normal? Both shutters are labeled as Copal 3.

They are the same size, but I am guessing you might have a copal 3s shutter. It is slightly smaller than the normal Copal 3. But both should fit on the lensboards with little difficulty(Unless you have a Copal 3s lensboard, which are very rare in my experience). What are the lenses you are trying to mount?

Hope it helps.

Gary

[Oren Grad]

SK Grimes has the Copal 3 and 3s specs here:

http://www.skgrimes.com/products/index.htm

[colrehogan]

The lens with the silver ringed shutter is a Fujinon-SF 250 mm and the one with the black ringed shutter is a Fujinon-C 600 mm. This is a board for a Century whole plate camera that I wanted to try the 600 mm lens on since I have the extension bed. I had previously used the 250 mm lens on this board with no problems. The 600 mm shutter has a 65 printed on it, so I assume that means the hole would need to be 65 mm?

[coriana6jp]

Thats the problem. The Fuji 250mm SF is a Copal 3s shutter and not a normal Copal 3. The Fuji 600C is a normal Copal 3, there is no way you can interchange those two lenses. I have both of these lenses as well and confirmed it.

You will need to correct board, ie one with a 65mm hole. If I remember correctly 250mm SF has a 59mm bore.

I am a little surprised though though Copal 3s boards are rather rare. What type of board is that lens mounted on?

Hope it helps.


Gary

[bobwysiwyg]

OK, another newbie question here. What determines if it will be Copal 0, 1, etc? Is it strictly up to the lens maker and the size of the lens barrel, or is there a correlation to lens size/focal length that will dictate this?

[Drew B.]

thats the size of the (required) hole in the lens board...

[coriana6jp]

I am certainly not an optical expert by any means, but its generally a combination of lens designs factors. Including, but probably not limited to Focal Length, maximum aperture barrel size. As aperture increases say a 240mm F/5.6 lens needs a copal 3 shutter, but whereas a 240mm f/9 can fit in copal 1.

Thats the simplified version, there are numerous formulas out there that determine all of the that. I have them around here somewhere if you are interested.

Hope it helps.

Gary

[bobwysiwyg]

Thanks, Gary. I can see how max aperture can be a big factor.

[Nick Zentena]

A #3 is more expensive and heavier then a #1/#0. For a lens aimed at the hiking crowd both can be issues. Think of the Fuji 450mm. It's F/12.5 while the Nikon in the #3 is faster. But if you're watching every gram the slower speed is an easy trade off.