Shutter equivalent to Copal #0

[eonore]

Please excuse this question if it is a dumb one, as I am about to be a newcomer to large format photography. I backed the Travelwide Camera project at Kickstarter, and I hope to get a camera soon. The project does look like it is winding down. I have located an Ilex lens of suitable focal length and aperture, but the lens comes with a Linhof synchro compur shutter instead of a Copal #0 as specified by the Travelwide people. Looking at the SK Grimes website, the Synchro compur and Copal shutters in the same size seem to have the same measurements. My first question is,assuming the Synchro Compur is a #0 size, is it interchangeable with the Copal for this application. and my second question is how do you determine the size of the shutter by looking at it, since the seller does not seem to know.
Thanks for any help you can give.

Eric

[Dan Fromm]

Compur and Copal shutters use the same size standards. Lenses that fit a #n Compur are direct fits in a #n Copal and vice versa. Similarly, a lensboard bored for a Copal #1 will also take a Compur #1 and vice versa.

If you want to use a lens in a #0 shutter in a board drilled for a #1, you can get a threaded bushing that a #1 retaining ring will screw on to and that a #1 shutter will screw into. SKGrimes sells them, so does B&H.

Quick way of determining the size (#) of a shutter that conforms to the Compur/Copal/Prontor/Seiko standard: unscrew the lens' front cell from the shutter, measure the mounting threads' outer diameter (or the inner diameter of the shutter's front tube). SKGrimes' site lists the sizes.

Note that shutters made in Rochester (Ilex, Kodak Supermatic, Wollensak Rapax/Graphex) don't conform to the Compur etc. standard. Lens cells in a "Rochester" shutter aren't direct fits in a Compur or equivalent.

[koh303]

Compur and Copal shutters use the same size standards. Lenses that fit a #n Compur are direct fits in a #n Copal and vice versa. Similarly, a lensboard bored for a Copal #1 will also take a Compur #1 and vice versa.

All true except for #3 shutters of which there are at least 3 different sizes, though the smallest is compatible across all compur/prontor and older copal #3 or 3S.

[eonore]

Thank you both for the information. It was very helpful.

Eric

[analoguey]

This was a question that I had in mind but hasn't asked! Good that you did Eonore!!
And thanks for the answers, Dan and Koh

[IanG]

Eric, usually you can be fairly certain what size a shutter is when you know what lens is in it, there's one common exception the early 90mm f8 Super angulons were in a Compur #00 shutter some Linhof Select as well.

The Wonderlust Travelwide camera is shown with a 90mm f6.8 Angulon in a Synchro Compur on their website, a lens never available in a Copal shutter.

Another small WA lens that could be used is the Wray f6.3 89mm WA lens often found in an Epsilon (Ensign) #0 shutter although some later ones are in Synchro Compurs.

Ian

[Emmanuel BIGLER]

A summary of leaf shutter specs, compiled from S.K. Grimes' web site


All dimensions in millimeters
size # _____________________ 00 ________ 0 ______ 1 _____ Compur-2(*) Copal-3s(**) __ 3
1/retaining ring thread ____ M25x0.5 _ M32.5x0.5 M39x0.75 M50x0.9 ____ M61.0x0.75 ___ M62.0x0.75
2/ring outer diameter ______ 26.1 ____ 34.6 _____ 41.6 ____ 52.2 ______ 64.0 ________ 65.1
3/lensboard hole diameter __ 26.3 ____ 34.8 _____ 41.8 ____ 52.5 ______ 64.2 ________ 65.3
4/font group mounting thread M22.9x0.5 M29.5x0.5 M40.0x0.75 M45.75x0.75 M56.0x0.75 __ M58.0x0.75
5/rear group mounting thread M22.9x0.5 M29.5x0.5 M36.0x0.75 M45.75x0.75 M56.0x0.75 __ M58.0x0.75
6/distance between group seats 16 __ 20.0+-0.025 20.0+-0.025 26.75 ____ 28.6+-0.025 __31.5


(*) There are several variants for the Compur-2, only one example is listed here
(**) size #3s exists only for Copal shutters

Lensboard thickness
All thicknesses in millimeters
Compur or Copal ; #0 : 1.5->4 #1 : 1.3 (Compur 1) or 1.5->3 #3 : 1.5->5
Prontor Pro ; #01S : 1.5->3 #1S : 1.5->3 #3 : 1.5->4
Copal Press ; #0 : 1.5->3 #1 : 1.5->2

Another compilation can be found here:
http://www.suaudeau.eu/memo/pratique/Les_obturateurs_centraux.html

For Compound shutters, sizes have been posted on this Forum by Ole Tjungen:
http://www.largeformatphotography.info/forum/showthread.php?23904-Compound-shutter-sizes&p=223663#post223663

[eonore]

Eric, usually you can be fairly certain what size a shutter is when you know what lens is in it, there's one common exception the early 90mm f8 Super angulons were in a Compur #00 shutter some Linhof Select as well.

The Wonderlust Travelwide camera is shown with a 90mm f6.8 Angulon in a Synchro Compur on their website, a lens never available in a Copal shutter.

Another small WA lens that could be used is the Wray f6.3 89mm WA lens often found in an Epsilon (Ensign) #0 shutter although some later ones are in Synchro Compurs.

Ian

The Travelwide campaign specifies that any 90mm F6.8 or f8.0 lens in a Copal #0 shutter should work. I have made a deal with a local guy to purchase an Ilex Acugon. He originally advertised it on Craigslist as in a Copal #0 shutter, but when he looked at it prior to transfer, he realized the shutter was not working correctly. He then substituted the Compur which fits and works. I think, therefore, I am okay.

Thanks for your comments, Analoguey, Ian and Emmanuel.

Eric

[Dan Fromm]

eeyore, you'll need the correct aperture scale for y'r lens' new shutter.

[eonore]

eeyore, you'll need the correct aperture scale for y'r lens' new shutter.

Dan, can you explain more fully what you mean. I am afraid I don't follow.

Eric

[Kevin Crisp]

The f:6.8 90mm angulon WAS available at the end of production in a Copal 0 shutter FYI. Serial number in the 11 range.

[Dan Fromm]

Dan, can you explain more fully what you mean. I am afraid I don't follow.

Eric

Eric, there's an iris diaphragm in the shutter. And there'll be an aperture scale on the side of the shutter or on the face plate, depending on which shutter it is. The numbers on the aperture scale (8, 11, 16, ... for an f/8 Acugon) indicate diaphragm settings at which the opening's diameter is 8/(diameter of the lens' entrance pupil) and so on.

When a shutter is delivered with a lens in it the aperture scale will be correct for the lens. Change the lens, as your seller did, and there's no guarantee that the aperture scale will be correct for the replacement lens. If the aperture scale is incorrect and you set aperture and shutter speed as your light meter or rule of thumb ("sunny 16") advises the film won't see as much light as you intend.

Oh, and by the way, there's a law of nature to the effect that a freshly-purchased used shutter's speeds are off. Another source of exposure problems. All freshly-purchased used shutters need at least calibration with a shutter speed tester and at best an overhaul.

[eonore]

Dan, please pardon my stupidity, but I have never handled a large format lens. Wouldn't setting f8 on the shutter produce an f8 aperture? What does it mean when you say that the aperture scale is correct for the lens? Does the lens have its own scale which must be matched somehow to the shutter scale?
I hope I am not missing something obvious. Thanks for your help.

Eric

[eonore]

Dan, please pardon my stupidity, but I have never handled a large format lens. Wouldn't setting f8 on the shutter produce an f8 aperture? What does it mean when you say that the aperture scale is correct for the lens? Does the lens have its own scale which must be matched somehow to the shutter scale?
I hope I am not missing something obvious. Thanks for your help.

Eric

I think I have answered my own question. If the lens that is now attached to the shutter has a different exit pupil diameter than the lens originally shipped with the shutter, the apertures may vary from the scale. Since I did not build in the expense of sending the lens and shutter for an overhaul, I am thinking of punting on this deal and finding one where the lens and shutter match.

[Dan Fromm]

You sort of got it. Its the entrance pupil, not the exit. And no matter what you do, if you buy a used lens in, naturally, a used shutter the shutter will be guilty until proven innocent. Budget for an overhaul.

Or shoot a high latitude b/w film and you'll be able to get away with exposures several stops off. I shoot mainly reversal film, which is very fussy about exposure.

[eonore]

Thanks Dan, you've really helped.