Remounting lens in Copal

[cunim]

My Rodenstock 120 apo macro sironar digital is in a Rollei shutte. That was a very capable solution for studio work with the IQ180 but, with the IQ4, I use the ES for timing and the Rollei just sets aperture. Bunch of additional kit and wires to do next to nothing.

So, I would like to remount the lens in a NOS Copal I have lying around. Easy enough with LF lenses, but spacing between the front and rear elements is critical for MF and I don't trust how the lens is shimmed now so it would best to start from scratch. I contacted SK Grimes and they do not have the ability to check element spacing as part of a remount. Rodenstock doesn't seem interested in doing it. Anyone know someone who can optimise element spacing as part of a shutter replacement?

 

[rdeloe]

You can! It's not hard. The key is that there is adjustment room. If there is adjustment room, it's a simple matter of setting up in front of a suitable target and adjusting the cell until you get optimum results. You'll need the correct thickness shim once you find the optimum distance. That's the hardest part.

 

[diggles]

Anyone know someone who can optimise element spacing as part of a shutter replacement?

Recently, I purchased a lens in a Schneider Electronic Shutter and remounted it in a Copal 0. On center it looked great, but I was not getting anywhere near the usable image circle that I should have. I sent it in to Christoph Greiner for a checkup. After inspection, they mentioned that it was not set up correctly so they will have to recalibrate it. This and information I've found in Schneider brochures makes me believe that spacing for an electronic shutter is different than spacing for a Copal 0 shutter. Lens specs in Schneider brochures show the FFD is different for Copal 0, Schneider Electric, and Rollei Electric shutters.

They informed me that they were able to complete the work successfully and everything is in spec. Now I'm waiting for it to arrive. It was supposed to be here Friday, but FedEx is a running late so it should be here tomorrow.

Here is their website:

Home

www.greiner-photo.de

It has a specific tab for Schneider-Kreuznach Service, but not Rodenstock. It looks like they sell Rodentstock lenses so this leads me to believe that they can service your lens, but I do not have first hand experience.

 

[Don N]

I have had several AO Rodenstock Digaron lenses remounted in copal by Rodenstock. They require that the copal shutter be one that has been used on prior rodenstock lenses- apparently there is some difference. Is the NOS shutter of Rodenstock vintage? If not, is this thethe reason they are not interested? If so, locate a gently used older copal equipped lens to sacrifice.

 

[Paul Spinnler]

Greiner is the last and only official SK service centre. W/o him, no SK lens repairs. He has original parts from SK and equipment to do all key servicing things, he is also the only one who will mount X shutters on SK lenses and make sure all is in spec incl. metadata readout.

 

[vjbelle]

Paul...... do you have a web address for Greiner?

Victor B.

 

[diggles]

Paul...... do you have a web address for Greiner?

Victor B.

Home

www.greiner-photo.de

 

[rdeloe]

Recently, I purchased a lens in a Schneider Electronic Shutter and remounted it in a Copal 0. On center it looked great, but I was not getting anywhere near the usable image circle that I should have. I sent it in to Christoph Greiner for a checkup. After inspection, they mentioned that it was not set up correctly so they will have to recalibrate it. This and information I've found in Schneider brochures makes me believe that spacing for an electronic shutter is different than spacing for a Copal 0 shutter. Lens specs in Schneider brochures show the FFD is different for Copal 0, Schneider Electric, and Rollei Electric shutters.

Funny you should say that... I started to wonder this last night thinking about the case of my two 35mm APO-Digitar L-88 lenses from electronic shutters, both of which came installed with shims. In contrast, a 35mm XL-102 in Copal 0 shutter I tried did not. I moved both of the L-88 cells successfully into a Compur 0 shutter (same specs as Copal 0). They needed slightly less space between the cells than they did on the electronic shutters. (A confounding factor is that on GFX, symmetrical wide lenses needed to be closer than 'spec' because of the cover glass.)

For it to be true that Schneider made different cells for mechanical and optical shutters, they would have to have made two completely different optical designs for the lens cells heading to electronic versus mechanical shutters. If they did that, I would expect to see three different optical formulations in published lens data sheets -- one for Copal 0, one for Rollei electronic 0, and one for Schneider electronic 0. I have the data sheets for nearly all of the Digitar lenses, and I have only ever seen one lens formulation per lens model. For example, here's the XL-102 version of the APO-Digitar 35/5.6. I have two versions of this data sheet, one from Alpa, one from Schneider, and the optical formulations are identical. Does anyone have an XL-102 data sheet with different lens data?

Another possibility that I think is more likely is that the electronic shutters from Schneider and Rollei have different spacing between the mounting surfaces than mechanical Copal 0 or Compur 0 shutters. I find this a lot more likely for two reasons. First, from a manufacturing point of view, it's vastly easier to use a common design for the lens cells regardless of shutter. Second, (and now I'm really wild guessing!) it makes sense that the electronic shutters have more adjustment room because of the tighter tolerances needed for digital. If you make the spacing between the mounting surfaces a tiny bit smaller, that gives you room for adjustment. Supporting this hunch is the fact that the two APO-Digitar 35/5.6 L-88 lenses I bought came with a total thickness of shims that far exceeds the Copal 0 spec (20mm +/- 0.025mm). Both of mine came with 0.21mm worth of shims. You'd need that much shimming if the mounting surfaces were closer together than on a mechanical Copal 0 shutter.

It's possible that the folks at Greiner know what's going on, but they're not going to be motivated to explain! That could be bad for business.

 

[cunim]

OK, so I obeyed @rdeloe. I made little chugging noises, chanted "I think I can" and remounted the cells. There are some real differences between the Rollei and the standard Copal mounting in the Arca boards. The hole for the Rollei shutter is larger, and the lock ring is too. Therefore, I used a standard 110 mm board, and the lock rings that came with my Copal. There was one thin shim on the back element and I retained that.

Put it on the IQ4/monolith and things look pretty much as they did before. The performance is acceptable but the only test I have done so far is to shoot a watch. Still need to look at the IC, after reading @diggles caution.

Rodenstock says all sorts of things. Some relate to the production date of the shutter, and some have to do with any modifications that were made so that the shutter would fit in its previous home. Early date and used shutter = bad. I sent them the SN of my NOS Copal and they said it was a pre-1980 model (bad) but it will still work with the apo macro sironar digital 120 (an old lens formulation, good). Sadly, it will not work with my 70HR, so I still need to figure out what to do with that. Rodenstock were not interested in doing the remount.

If Greiner will do Rodenstock, that seems like a good way to go with the 120. Not only to check spacing, but the shutter time setting in that almost 50 year old Copal has gotten stiff and I am sure he can take of that. I'll send a message.

Thanks everyone.

 

[daz7]

eletronic shutters use Copal 1 size for lens board thread and retaining rings but the cells are still Copal 0 and can be swapped to a Copal 0 shutter. You may or may not need to adjust the spacing, depending on how lucky you are to have a copal shutter adhering exactly to specs.
You will alwyas need a shim when going from a Copal shutter to an electronic shutter as these are slightly narrower and made up to specs by adding shims. When going the other way it is not always the case, sometimes you may be lucky enough just to screw in your cells and be ready to go.
Before sending your shutter for service, you may want to take some shots to check how it works. It may turn out that it works perfectly fine and no further adjustment is needed. If you need to adjust it, you can start undoing the front cells by small increments, let's say quarter turns until you find the best position. Then work out the spacing needed and try to get shims (which may be quite difficult). Or send your lens and shutter for full service.
You will obviously need a new lens board (copal 0 size) as the existing one is for Copal 1 shutters and electronic shutters.

 

[rdeloe]

You will alwyas need a shim when going from a Copal shutter to an electronic shutter as these are slightly narrower and made up to specs by adding shims. When going the other way it is not always the case, sometimes you may be lucky enough just to screw in your cells and be ready to go.

Can you clarify: which ones have the shorter distance between mounting surfaces? Electronic or mechanical?

Also, do you know why the flange distances are different for these lenses in the different shutters? I've always wondered about that, and Warren noticed it too in his post (above). If the optical formula for the cells is the same, which appears to be the case, how can the flange focal distance be different?

 

[rdeloe]

The plot thickens... I was trying to track down the specifications for Schneider and Rollei electronic shutters and found this data sheet for some other ones.

The "Compur electronic m 0" shutter is nominally Copal 0 spec, but the distance between the faces of the front and rear elements is 20mm +/- 0.04mm. For the "Prontor magnetic 0" it's 20mm +/- 0.03mm. For mechanical Copal 0 it is of course 20mm +/- 0.025mm. https://pyramidimaging.com/specs/Schneider/Shutters_Overview.pdf That may not seem like a lot, but with the wide lenses it's enough to make a significant difference in image quality.

This is where the "crap shoot" side of remounting lens cells really bites. The more I learn about this the more I realize that I was very lucky to find a Compur 0 shutter that appears to have been on the minus side of the specification, because that gave me enough room to get the cells of the APO-Digitar 35mm f/5.6 L-88 lenses I bought closer together than would otherwise be possible.

 

[DNN]

.....

Rodenstock says all sorts of things. Some relate to the production date of the shutter, and some have to do with any modifications that were made so that the shutter would fit in its previous home. Early date and used shutter = bad. I sent them the SN of my NOS Copal and they said it was a pre-1980 model (bad) but it will still work with the apo macro sironar digital 120 (an old lens formulation, good). Sadly, it will not work with my 70HR, so I still need to figure out what to do with that. Rodenstock were not interested in doing the remount.
......

For the 70HR - watch ebay for a copal 0 mounted rodenstock lens to sacrifice. Condition could be a crap-shoot but when Rodenstock remounts, they do a check on the copal and will tell you if no good. All of my remounts in copal 0 from sacrificial lenses were great and work very well,

 

[daz7]

From experience (and I have only had two electronic shutters), the spacing between mounting faces were slightly lesser than those of copal mechanical shutters. The difference was around 0.2mm and there was always a shim in electornic shutters to compensate for that.
In my eyes, it looked like electronic shutters were made slightly narrower for purpose, to make sure that they would not 'overshoot' mechanical shutters specs. I do not know if my theory based on two cases is valid or not, but I assumed that the reason for shorter spacing is to prevent manufacturing tolerations putting them above copal specs, which would be disastrous and not correctable.
Having a shorter distance can be corrected by shims, after all and that's what I was finding in elecronic shutters.

Again, as my observation is based on two specimens it may be far from the general rule, but it made sense to me.

I no longer have electronic shutters to check the exact measurement. If @cunim now has a spare one, would be great to know what is the exact distance betwen the front and rear mounting faces and if he had a shim in his shutter. I bet, there was a shim of 0.2mm thickness.

 

[rdeloe]

From experience (and I have only had two electronic shutters), the spacing between mounting faces were slightly lesser than those of copal mechanical shutters. The difference was around 0.2mm and there was always a shim in electornic shutters to compensate for that.
In my eyes, it looked like electronic shutters were made slightly narrower for purpose, to make sure that they would not 'overshoot' mechanical shutters specs. I do not know if my theory based on two cases is valid or not, but I assumed that the reason for shorter spacing is to prevent manufacturing tolerations putting them above copal specs, which would be disastrous and not correctable.
Having a shorter distance can be corrected by shims, after all and that's what I was finding in elecronic shutters.

Again, as my observation is based on two specimens it may be far from the general rule, but it made sense to me.

I no longer have electronic shutters to check the exact measurement. If @cunim now has a spare one, would be great to know what is the exact distance betwen the front and rear mounting faces and if he had a shim in his shutter. I bet, there was a shim of 0.2mm thickness.

This makes a lot of sense and matches my hunch from above. There were more shims in the two Schneider electronic shutters I bought than needed for mechanical shutters.

 

[cunim]

I no longer have electronic shutters to check the exact measurement. If @cunim now has a spare one, would be great to know what is the exact distance betwen the front and rear mounting faces and if he had a shim in his shutter. I bet, there was a shim of 0.2mm thickness.

I do have the shutter here but I am not sure where to make any measurement. The elements move on a threaded core and my micrometer will not get in there to measure the front and rear faces.

There was a shim on the front element 0.20 mm.

 

[rdeloe]

I do have the shutter here but I am not sure where to make any measurement. The elements move on a threaded core and my micrometer will not get in there to measure the front and rear faces.

There was a shim on the front element 0.20 mm.

Indeed. Assuming you can lock the shutter open, I don't know how it would be possible to measure the spacing between front and rear mounting surfaces. It's not obvious where to start and where to end, and we're looking for differences as small as 0.025mm.

Someone has the equipment and knowledge to measure this, but it's not me! I use an empirical approach: (1) Screw the cells in. (2) Does it work? (3) If it doesn't work, try a different housing.

 

[Reginald Fluggelding]

I do have the shutter here but I am not sure where to make any measurement. The elements move on a threaded core and my micrometer will not get in there to measure the front and rear faces.

There was a shim on the front element 0.20 mm.

What I have done, which is a little bit ghetto as they say, is to measure the length of the entire lens in the original shutter. If you can put it into the new shutter and match the measurement it should be good. I've done this with a dial gauge indicator which measures to 0.01 mm. With very small measurements you can more or less read half way between the markings for better precision but it's technically outside of the tolerance of the gauge. There are more expensive gauges with higher precision.

Ideally you need a calibrated surface plate to put the lens on for the measurements. I don't have one but managed to get some good readings using a 30mm thick sheet of melamine. The dial gauge goes on a heavy stand and you put the original lens between the gauge and the surface plate, zero the dial gauge, replace the shutter, put it back under the gauge and check the difference. You should move the lens around and take measurements at various locations. If everything is set up well the dial gauge reading should not fluctuate as you move the lens around. It is quite awkward resting the gauge plunger on the edge of the lens barrel so I rested a glass lens filter on top as a reference surface to take readings off. The actual height of it doesn't matter because you are just looking for any difference.

With a proper surface plate and gauge stand you can move the gauge around relative to the lens but I think moving the lens is more accurate and less prone to error. A test indicator instead of a plunger style indictor may be even more accurate and easier to take the measurements from the actual lens barrel, however using the filter as a reference surface isn't bad as it averages out any imperfections that could be in the metal barrel.

I was reshuttering a lens from a SINAR DB mount hence my calibers weren't big enough to take the measurement. Doing it the way I have described also avoids errors from not keeping the calibers or micrometer perpendicular to the object you are measuring.

I've also done what rdeloe suggests with another lens I have, on my Cambo with the IQ4-150. Using live view and a distant object to focus on and taking some frames to compare at 100%. I reshuttered a SINAR 55 mm digital lens to Copal and wanted to check whether the spacing was effecting performance (was great on the Leaf Credo 60, could start to see limitations on the IQ4). The measurement with the gauge is a good starting point though.

All of this depends on the lens being in spec in the original mount so results could vary.

 

[buildbot]

What I have done, which is a little bit ghetto as they say, is to measure the length of the entire lens in the original shutter.

That’s pretty clever in my opinion!

 

[Reginald Fluggelding]

That’s pretty clever in my opinion!

Thanks! I can't really take much credit though, I think it's pretty basic kind of stuff that engineers do for precision measurements. Maybe using a brick, a Manfrotto super clamp and a magic arm as my gauge holder I can take credit for though.