"Procedure" ;)

[pgk]

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12 minutes ago, luigi bertolotti said:

Yes, many 5cm 2,9 existed (Schneider, Cassar & Others) ... this one is from a Certa Dollina... the plate with f stops values is of course very easy to dismount/remount

Compur shutters usually need to be carefully positioned and certainly those for large format lenses need to be set up accurately for each individual lens. Changing one over is not a simple matter of unscrewing it and refitting it.

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[zeitz]

9 minutes ago, pgk said:

Compur shutters usually need to be carefully positioned and certainly those for large format lenses need to be set up accurately for each individual lens. Changing one over is not a simple matter of unscrewing it and refitting it.

Paul, is the positioning related to placing the shutter blades at the nodal point of the lens?

Off the topic, but I find it curious that some lenses can have the aperture behind all the lens elements.  The Carl Zeiss Jena 300mm f4.0 Sonnar is an example.

[luigi bertolotti]

24 minutes ago, pgk said:

Compur shutters usually need to be carefully positioned and certainly those for large format lenses need to be set up accurately for each individual lens. Changing one over is not a simple matter of unscrewing it and refitting it.

Yes, I simply referred to the plaque in itself... the depicted Leica has been surely reworked but the lens is surely an Elmar...  probably they used a mix of parts to complete the job, and had available that plaque.

[pgk]

6 minutes ago, zeitz said:

Paul, is the positioning related to placing the shutter blades at the nodal point of the lens?

Off the topic, but I find it curious that some lenses can have the aperture behind all the lens elements.  The Carl Zeiss Jena 300mm f4.0 Sonnar is an example.

The positioning of the aperture is something I've seen a lot of discussion about. It can be varied somewhat but this depends on the design I think. However ,it is important that the cells either side of it retain their precise designed position relative to each other, and this is the tricky bit because, as far as I can ascertain, the compur shutters vary slightly in their tube dimensions. So the mounts for the lenses sections need to be machined, threaded and adjusted accordingly.

[zeitz]

6 minutes ago, pgk said:

it is important that the cells either side of it retain their precise designed position relative to each other

Now I understand.  Thanks.  SK Grimes (The Photographers Machinist) in the US is a specialist in mounting lenses to shutters.

[jc_braconi]

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[willeica]

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4 hours ago, luigi bertolotti said:

the depicted Leica has been surely reworked but the lens is surely an Elmar.

See my previous post above. I have 5 such lenses. The lens shown by the OP is one which was sent to Nagel by Leitz in 1932. Leitz were supplying Nagel with lenses at that time. I have two Nagel Pupilles and a Nagel Vollenda with this exact type of lens. I also have one on a Welta Weltini II and one that came on a Kochmann Korelle K , but it was the wrong lens and I have since traced the correct one. Several lenses with 5cm f2.9 came on Compur mounts including the Meyer Gorlitz lens on my father's Super Baldina from 1940. This one looks like a number of swaps were done to both the camera and the Compur, but we can say that it is a Compur Leica, just not one of the ones that collectors pay large amounts for. If it is properly put together the camera should produce nice photographs. Cameras with Compur shutters need to be properly adjusted by a skilled technician. My CLA man showed me the inside of my 10.5cm Leitz Elmar in a Compur mount as it was being repaired and it was very complex and definitely not for unskilled hands.

I will try to find a way of posting my slides or a link to them for my Compur presentation next month. 

William 

[jerzy]

vor 10 Stunden schrieb willeica:

but we can say that it is a Compur Leica

Compur Leica is commonly used synonym for model IB which this camera is not and never was. More adequate would be to call it "Leica with Compur shutter".Compur Leica was concepted and built as cheaper alternative to IA, interior shows significant differences to IA. Conversions from/to IB was not offered and not possible.
Camera 16483 should have 4 screws for the top plate.
William, I agree that Compur is not easy to repair, it is more precise mechanism than usual Leica shutter. But as usual - if you have tools and understanding what you are doing than as well Compur may be restored

Edited December 24, 2021 by jerzy

[willeica]

2 hours ago, jerzy said:

Compur Leica is commonly used synonym for model IB which this camera is not and never was

 

13 hours ago, willeica said:

but we can say that it is a Compur Leica, just not one of the ones that collectors pay large amounts for.

I agree and that is what I said. This is a camera not wholly constructed by Leitz, but it is a Leica with a Compur Lens set up. It is not a I Model B, of course.

For those who might be tempted to work on a Compur shutter/mount, my advice is don't. Give it it to someone like Jerzy or my CLA man, Noel Young, here in Dublin. Here are some photos of my Leitz 10.5 cm Compur lens as it was being serviced by Noel. Some of the parts are tiny. The 10.5 cm lens was originally for a Nagel Recomar. I intend to use it on a 5x4 camera.

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William