Rodenstock 90mm f6.8 filter thread

[Tumbles]

I have this Rodenstock 90mm f6.8 with an issue that's driving me crazy. It seems like the thread for the filter is not standard. It's listed as taking a 67mm filter, and I've tried five different filters of this size and none of them have fit. It's like all of them are slightly too big. I can get the thread to catch, and I can get maybe a half turn before it stops. The filters end up tilted, like you would see if you cross threaded something.

Does anyone know anything about this? Was there a version of these made that had a weird filter thread, or do I just have a strange lens? It looks like the only solution is to get someone to make a custom adapter.

 

[Doremus Scudder]

My literature lists your lens as having standard 67 x 0.75mm filter threads.

Sounds like your lens may have been dropped or bumped at some point, slightly deforming the lens barrel/threaded filter ring. A good repair shop may be able to chase the threads and restore the ring to its original shape.

Best,

Doremus

 

[Sean Mac]

67mm on my one.

A few measurements with a caliper or even a rule across the diameter at a few angles will show if it's truly round. Even a small discrepancy will create the problem you describe.

Good luck with it, my example is a nice lens.

 

[AgX]

A spoiled thread seems more probable. Check meticulously the thread with a loupe, run it with a fingernail. A tiny indent just at one point of a thread flange may make the whole thread useless unless cut off.

But still, a small distorsion may be the cause too. Maybe the lens fell onto/bumped into something soft, so that the resulting indent not obvious. As indicated use a caliper to establish such. In such case you may consider pressing at both sides at 90° distance to the indent.

 

[Tumbles]

The lens barrel being distorted makes the most sense to me in this case. It's too subtle to really see. I measured it vertically and horizontally, and I'm getting a 0.007" difference. My caliper is in inches only, so it should be 0.1778mm in metric. If this is enough to cause a problem, I wonder one goes about fixing it?

I checked the threads and they seem fine for the most part. There are a few rough spots that I created by trying to screw in filters.

 

[xkaes]

It doesn't take much at all to mess things up. Sometimes the kink can be very hard to see. If you can find it, it might be able to repair it fairly easily -- especially if it is small.

Pretty frustrating. The fact that you can kinda get it in is the real test. It's kinked somewhere. Do you have a workshop?

I fixed two SMALL dented filter rings last week. They are not perfect, but good enough.

You might want to start a discussion on the CAMERA REPAIR sub-forum.