Correct way to set up a Copal 3 Shutter

[luciano_capitanio1]

The Copal 3 shutter has a two pieces retainer: an aluminium spacer

ring (about 4-5 mm thick) and a threaded retainer. What is the

correct way to assemble the shutter on a metal flat lensboard (I

have a Cambo, but I think it's the same with Sinar, Toyo and Linhof

Kardan lenboards)? With the ring behind or in front the lensboard? I

tried both ways and it seems always ok (of course if I set up the

ring behind the lensboard, the rear surface of the shutter is very

near to the lensboard, othewise it is 4-5 mm far...)

Thank you

[michael_briggs2]

AFAIK, you can mount it either way on some cameras. On other cameras with smaller lensboards, you need to use the spacer ring in front of the lensboard to space the shutter a few mm in front of the lensboard, since, without this spacing, the shutter would prevent the lensboard from fitting onto the camera.

[thirteenthumbs]

Put the spacer between the shutter and lens board.(increased clearance of levers, ect)

[will_groff]

Understanding that a spacer 'lifts' the shutter off the board, if one was trying to set up a lens at the manufactured infinity distance, film plane to flange distance, would the flange measurement be taken from the surface of the spacer to the film plane, or would the measurement be taken from the back of the shutter itself to the film plane? This has been a question I've wondered about for quite a while, what do folks think?

[dan_fromm2]

Bill Groff asked "Understanding that a spacer 'lifts' the shutter off the board, if one was trying to set up a lens at the manufactured infinity distance, film plane to flange distance, would the flange measurement be taken from the surface of the spacer to the film plane, or would the measurement be taken from the back of the shutter itself to the film plane?"

 

Every question deserves a question in return. Why would anyone treat a lens' nominal focal length as anything but nominal? That is, why would anyone take it very seriously?

 

I've owned 20 ex-RAF ex-AGI F135 38/4.5 Biogons. Each had its focal length, measured to .1 millimeter, marked on the AGI (not Zeiss-supplied) barrel and each had a spacer, measured to .01 millimeter to ensure that when the lens was mounted to the camera body it would focus at infinity.

 

AGI and the RAF were very serious about their cameras. They measured focal lengths, didn't take it for granted that lenses manufactured to very tight QC standards really had exactly the nominal focal length. FWIW, some did, others didn't, the range I saw was 38.3 - 38.8 mm.

 

If your camera has infinity stops as press cameras do, surely you set them up as press camera infinity stops are supposed to be. Namely, by focusing the lens to infinity, not with a ruler.

 

Cheers,

 

Dan