removing large-format shutter aperture click stops

abruzzi

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I have a number of lenses that have click stops on the aperture dial. The one I'm most interested in undoing this to is a later Compur 3, mostly because I'm going to have to re-do the aperture scale, and I'm wondering if the clicks won't line up with the major numbers any more. I'm not sure whether my others are Compur or Copal (not near them at the moment.) but just from a general perspective, is this major surgery, or is it easily done? Does anyone have links to info on how to do it, or should I bite the bullet and send it off? (I understand it will be different between Compur and Copal, and may also be different for different size or generation shutters, but any info would be interesting.)
 

BrianShaw

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It has been a while since I used some of my LF gear. They all have clicks for shutter speed but I don't recall any of them having clicks for aperture. While clicks on aperture are useful for small- and medium-format shutters, I would find that very annoying for a large format application.

In the Compur Nr3 parts diagram/list, I see the click for shutter speed but nothing that appears to be a click for aperture. Are you sure?
 
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abruzzi

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Yup. I’ve read somewhere that it was a Schneider thing, that they specifically modified some of the shutters to put clicks in. Now that I checked my SA 90mm f5.6 clicks, my SA 90mm f8 clicks, both in synchro-Compur #0 shutters, and the Compur #3 that bought recently has it as well.
 

BrianShaw

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Hmmm. I’m surprised. All of mine are in Copal and have no click on aperture so I guess I’m lucky. Clicks on shutter speed make perfect sense; on aperture could be quite annoying. Does it click at 1/3 stop intervals? If so, you might get lucky that a change in aperture scales might be close enough.
 
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abruzzi

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I removed one of my Compur #0 shutters, and removed the elements so I could take a good look. You can see the aperture lever on the right, it is part of the toothed plate, and you can see something that engages the teeth. The trick would be to remove that piece (or bend it out of the way.



there is a small metal screw, below the PC flash port. You can see it blurry in the photo. This one has half stop clicks.
 

BrianShaw

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It looks as if the teeth interface with the black tab wit the "out-dent" (on the right of the teeth in the picture). Flattening that might do the trick. Or, if its nothing more than a spring-loaded clicker it might be removable.

I've never seen such a setup; thanks for the picture!
 

Alan Edward Klein

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I wish my 4x5 lenses had stops for the aperture. If you want to add a stop, indents allow you do this without looking. Why arent;t they helpful for LF?
 
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abruzzi

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The other two (the Compur #0’s) are clearly the original shutters for the lenses that are mounted, so if I can’t find an easy de-click, it’s no huge loss. I do also wonder if the aperture dial will feel too loose after declicking? I love the resistance on my later Copals but it occurred to my that the click holds the aperture in place, so it may not have as much moving resistance.

I can see how the click could make things easier if you want to stay behind the camera, but at this point going back to the front of the camera to set aperture, shutter speed, and cock and test fire the shutter, is a normal part of my process, so I prefer the smooth action of my Copals. I haven’t disassembled the Compur #3 yet to see if it works the same way, but I do remember the teeth on the aperture ring, but I always assumed it was part of the later Compur setup for adjusting the shutter from behind the lens (sort of like the Sinar shutters, but without the single shutter.
 

David Lindquist

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Carol Flutot states on her website that some Copal shutters from Schneider have aperture click stops. She further says Schneider does/did not provide spare parts for this feature. Don't know when Schneider started providing this feature. My newest Schneider lens was made between January 2001 and January 2002. Its No. 0 Copal does not have click stops for the aperture.

I have two No. 1 Compur shutters, one with a lens made in 1975, the other with a lens made 1979-1981. Both have an aperture click stop mechanism that looks like that shown above. Also both have a top speed (nominal) of 1/500 vs 1/400 for earlier No. 1 Synchro Compurs.

David
 
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abruzzi

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Interesting about then1/500. The Compur #3 I have has an indicated 1/200 instead of the usual 1/125 for #3 shutters. Anyway, I removed the rear element and lens board from the #3 and it seems to have essentially the same mechanism, but I’m almost certain I’ll have to open it up to figure out how it attaches.
 

David Lindquist

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I think the late versions of the Compur shutters used a different sort of main spring which gave a higher top speed than the earlier versions of the No. 1 and No. 3. Also the older No. 1 shutters give a feel of greater resistance when moving the setting from 1/250 to 1/400. My two newer No. 1 Compurs do not do this when changing the setting from 1/250 to 1/500 (nor do any of my No. 1 Copals when going from 1/250 to 1/400). I think the late versions of the Prontor also had a higher top speed than the earlier versions.

I wonder if competition with Copal was behind this and the hope was a higher top shutter speed would make the higher price of the Compur seem worth it.

David
 

AgX

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abruzzi said:
I do also wonder if the aperture dial will feel too loose after declicking?
Click to expand...

Good point, but you should be able to bend off that spring so that it just not engages in the click-stop serrations and test the dial. In case it is to loose you may consider if you disassemble that dial to apply damping grease. Which might not be the best idea with escapements nearby. Alternatively you might cut out a strip of brass, bend it and lay it on the serrations under the spring and glue it to that spring.
 

mpålsson

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The Apo-Symmar-L series, which was introduced in 2002, and the Apo-Tele-Xenar Compact MRC series, which was introduced some time after that, as well as many of Schneider’s digital lenses are mounted in Copal shutters with click-stop apertures. I’m not sure about the XXL or original (white front with blue stripe) Apo-Tele-Xenar lenses. All earlier lens series (Super Symmar XL, Super Angulon XL, Apo-Symmar, etc) came mounted in regular Copal shutters.
 

David Lindquist

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And I recently got a 90 mm f/6.8 Angulon, made 1969 to mid-1970, mounted in a No. 0 Compur. It has click stops, in half stop steps. The two No. 1 Compurs I mention above click in one third stop steps. None of these have intermediate marks on the diaphragm scale.

I also have a 6 inch Gold Dot Dagor, about the same vintage as this 90 mm Angulon mounted in an identical looking No. 0 Compur. It does not have click stops.

David
 

BradS

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Seems odd...none of the 20 or so large format lenses I own (Copal and Compur shutters) have detents on the aperture ring.
 
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abruzzi

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BradS said:
Seems odd...none of the 20 or so large format lenses I own (Copal and Compur shutters) have detents on the aperture ring.
Click to expand...

Its definitely not common, but seems to be associated with Schneider of a certain era, though not universal (based on Davids comment) I have three shutters this affects. All are Compur, two are #0 shutters with Super Angulons in them (one ƒ8 and one ƒ5.6). The other is a Compur #3 that I bought bare, so I don't know what lens was in it.
 

David Lindquist

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To add a bit to my earlier post #15 of October 9, 2021: The lens made in 1975 is a 135 mm f/3.5 Zeiss Planar, Linhof Select. The lens described as made in 1979-1981, well its manufacturing date can be narrowed down to October 1979 - Jan 1981, probably earlier in this time frame and it is a 180 mm Symmar-S, multicoated, also a Linhof Select lens.

Build date of the Planar is from Hartmut Thiele's Fabrikationsbuch Photooptik III Carl Zeiss Oberkochen. The Symmar-S is dated from the serial number information that used to be on Schneider's website, thanks to Dan Fromm it is still available to us.

Again both the No. 1 Compurs for these lenses have click stops, clicking at 1/3 stop intervals.

Here's the Schneider serial number info: http://web.archive.org/web/20121115075344/http://www.schneiderkreuznach.com/service/serie.htm

David
 
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