View Full Version : washer in Rodenstock lens

11-Mar-2008, 09:59
I saw two 210 apo sironar S first one(112XXXXX) has two washer, the second one(115XXXXX) has only one washer. What is the correct number of washers in this lens?

David A. Goldfarb
11-Mar-2008, 10:01
You could ask Rodenstock, but it's possible that lenses are shimmed individually to compensate for slight differences in focal length due to differences in the refractive index in the glass, so both of these lenses might be adjusted as they should be.

Bob Salomon
11-Mar-2008, 10:46
The correct number will vary from lens to lens and shutter to shutter. Since variations occur in any manufacturing process the number of shims will never be the same. The thickness of shims may also vary. In some lenses there may be no shims involved.

Since one of the reasons shims are used is due to mechanical variations in shutters it is possible that a lens in one shutter uses shims and when you purchase a new shutter for that lens a repair center may find that for that specific new shutter no shims are required. Or more shims are required or fewer shims are required.

That means that it is very important that if you take the front and/or rear groups off a shutter that you replace any shims exactly as they were when you put the lens back together on that shutter. Otherwise the performance will not be up to factory spec.

john borrelli
12-Mar-2008, 08:17
Bob does Rodenstock always put the shims between the shutter and the lens's front cell in their apo sironar series. It would seem that shims put between the rear cell and the shutter would more likely to be lost when mounting or unmounting the lens on the lens board. Thanks for any info.

Bob Salomon
12-Mar-2008, 12:23

I believe that they are usually in front but we have seen them in both the front and back on one lens. Not usual though.

john borrelli
12-Mar-2008, 20:43
Bob, thanks for your prompt reply.

15-Mar-2008, 06:52
If you are replacing any late model shutter with another late model shutter of the same size, it is unlikely that you will see any variation in mounting thickness. The thinnest shim that I have ever seen on a Rodenstock or Schneider lens is 0.01mm. Current shutters are held to tolerances much closer than this. If, however you are dealing with an older shutter or one that has been disassembled for service, all bets are off. The shims are used by the factory to account for production variations in the lens cells, not the shutters.