Will my Dagor fit a Copal No. O?

[ajmiller]

The Compur shutter for my Goerz-Dagor f9 10cm lens has gone kaput! The repair shop said it can't be fixed. The only shutter I have spare contain a G-Claron 150mm. It's a Copal No.o but it's f11. Will the dagor fit the Copal? Thanks

 

[lobitar]

Provided the Dagor-Compur has a shutter mounting flange of 32,5 mm (which I think it has), then the Dagor should fit into the Copal-0 no problem. The aperture scale won't fit however. Just unscrew the front and rear groups of each lens (- and presto you may have sort of a casket set to boot?).

 

[ajmiller]

Thanks - yes it does fit (should have worded my question better) - it is the f11 that I wondered about.

 

[lobitar]

In that case you just have to apply a (millimeter)rule across the front lens, so as to measure the diameter of each aperture stop in mm and compute it as part of 10 cm (100mm). No big deal! If you is only reasonably careful when measuring, then I've had no problems, no matter if small or large lenses.

 

[ajmiller]

In that case you just have to apply a (millimeter)rule across the front lens, so as to measure the diameter of each aperture stop in mm and compute it as part of 10 cm (100mm). No big deal! If you is only reasonably careful when measuring, then I've had no problems, no matter if small or large lenses.

Ok thanks. I'll have to get my head around that one.

 

[Donald Qualls]

you just have to apply a (millimeter)rule across the front lens, so as to measure the diameter of each aperture stop in mm and compute it as part of 10 cm (100mm).

Your aperture ratio (the f/ stop) is the inlet pupil (aperture as seen through the front lens group) as a fraction of the focal length. So in your case, if you find a measured aperture of 9 mm on your 10 cm focal length lens, you've got f/11. You can make your own scale, just a piece of paper glued in place of the one from your G-Claron and marked with the lever position at which you see the correct aperture diameter (through the front lens group!) for each aperture stop. So f/9 would be 11 mm, f/11 is 9 mm, f/16 is ~6 mm, f/22 is 4.5 mm, and f/32 is ~3 mm. Probably don't want/need to go smaller than that with a 100 mm lens...

If you have click stops, measure at each of those and mark the scale for the correct value. I don't think any of my large format lenses have click stop apertures, but I'm sure there are a few that do...

 

[ajmiller]

Thank you Donald, that was really useful.

 

[RalphLambrecht]

Ok thanks. I'll have to get my head around that one.

not difficult; N(fstop number)=f(focal length)/a(aperture or lens opening)

 

[Joe Kashi]

Compur variants sometimes had different tube lengths such that the overall front to back length of the two combined cells would differ even though the individual cells screwed in OK on each end.

The image quality of some Dagor and other lenses could sometimes be negatively affected rather drastically if the front to back distance varied depending upon which tube number was mounted on the basic shutter assembly.

One rough way to initially check this is to mount your two cells in the old, dead shutter and measure the total front to back distance, Then, transfer the cells into the new shutter and repeat the measurement. If they vary by more than 1, maybe 2 mm, then you may have an image quality problem when using the new shutter.

 

[ajmiller]

Thanks Joe.

 

[JPD]

I wonder why the Compur can't be repaired when there are plenty of functioning ones of that size out there that could donate spare parts? Maybe it's just a broken retard gear train.

 

[ajmiller]

I'd love to get it repaired! I only tried my usual repair man who had always done a great job. Unfortunately, he was at the end of his working life before he retired so maybe it wasn't something he fancied doing. I'm UK based and there doesn't seem to be that many repair shops left but I will have a look around. Thanks

 

[David Lindquist]

Maybe some suggestions here of places in the UK: https://www.5x4.co.uk/threads/compur-1-shutter-service.2595/

In particular on their website Linhof & Studio includes this statement: "We also undertake most large & Medium format shutter services."

David

 

[ajmiller]

Thanks David. In searching did find uk based Newton Ellis who do Compur shutters. They’re closing down end of December so suggest getting any repairs in by end November. I’ll be posting tomorrow. Thanks for all the suggestions.

 

[David Lindquist]

Here's hoping it can be fixed. Personally I like to see lenses like this kept original if possible.

Incidentally per Hartmut Thiele's Fabrikationsbuch Photooptik II Carl Zeiss Jena Your lens is one of a batch of 50, serial numbers 2,214,701-2,214,750, production of which started December 18, 1937.

David

 

[ajmiller]

Here's hoping it can be fixed. Personally I like to see lenses like this kept original if possible.

Incidentally per Hartmut Thiele's Fabrikationsbuch Photooptik II Carl Zeiss Jena Your lens is one of a batch of 50, serial numbers 2,214,701-2,214,750, production of which started December 18, 1937.

David

I hope so too. Following my usual repair guy telling me it couldn't be repaired I sort of gave up on the idea of it been fixed - without contemplating a second opinion. I spoke to Newton Ellis today and the guy said they could repair Compurs so it's packed and going tomorrow. Thanks for the info on the lens, it's a favourite of mine - the photos from it have a certain look that appeals to me. I have been using it on my Sinar with the auto-shutter - a bit of overkill but it does the job for now.

 

[maruti660]

Hi, my Dagor 10cm f9 was in the opposite situation to yours, originally it was fitted with Copal #0. Copal was good and accurate but I didn't like its heptagonal shape. It would appear backwards in close-up shots. So I looked for Comper #0. There are very few good ones these days, and few workshops willing to do proper maintenance, so I had a hard time finding a repair person. Although it has a 10-sided aperture, the bokeh is more beautiful than that of 5- or 7-sided apertures. So I think it's a good idea to look for a Compur lens like me. Of course, the operation of focusing is easier with Copal.

 

[ajmiller]

Thanks for posting this. Reminded me I hadn't updated. The shutter was repaired by Newton Ellis last year (before they closed for business). It works well again now. Only thing is now I'm not sure I like a 100mm lens on 5x4......Eeek!

 

[maruti660]

It is sad to see so many excellent repair shops going out of business. The same is true here in Japan. Actually, I originally purchased this lens as a 5x7 format lens. I was surprised that such a small lens had such a wide image circle. It's amazing that such a lens was made in Germany in the 1930s...

 

[Dan Fromm]

I was surprised that such a small lens had such a wide image circle.

If you want a large surprise, look at a f/14 Perigraphe Ser. VIa or a f/18 Protar Ser. V.

 

[Donald Qualls]

Of course, the operation of focusing is easier with Copal.

Is this because of the bokeh shape, or some other reason? I'd have expected, strictly on an optical basis, that focusing at a given aperture would be the same regardless of the shutter the lens is mounted in.

 

[Dan Fromm]

Is this because of the bokeh shape, or some other reason? I'd have expected, strictly on an optical basis, that focusing at a given aperture would be the same regardless of the shutter the lens is mounted in.

Perhaps maruti660 doesn't know how to operate the Compur' s press focus mechanism.

 

[maruti660]

Is this because of the bokeh shape, or some other reason? I'd have expected, strictly on an optical basis, that focusing at a given aperture would be the same regardless of the shutter the lens is mounted in.

Hi Donald, Sorry for the lack of explanation, I mentioned the shape of the blur depending on the number of aperture blades. Copal #0 has seven blades, so the blur in the background is naturally heptagonal. In normal shooting, it hardly bothers me. However, when I get extremely close to the subject, for example, the shape of the sunlight filtering through the trees in the background all becomes heptagonal, which I couldn't stand. That's why I looked for a shutter that could be attached.

 

[maruti660]

Hi Dan, thanks for the comment. I know how to do that very well. That being said, I think the Copal is easier to use in terms of structure because the shutter can be opened and closed at any time. But if you ask me which I prefer, I would say Compur