Screw missing on enlarging lens

Marco Buonocore · Mar 18, 2017

I've got this Rodagon G 105mm lens, and there is a screw missing on the aperture ring. Consequently, you cannot adjust the aperture.

What are the chances anyone can tell me what size of screw I need for this? If I find the right screw, how do I know where I should be fastening the screw into the barrel?

Any advice welcome!

AgX · Mar 18, 2017

Concerning your first question: It very likely is a metrical thread. Just try a few for a fit.

Marco Buonocore · Mar 18, 2017

I found this image on an old ebay listing, and it gives me an idea as to where to fasten the screw on the lens. I will try a metric one, thanks AgX!

AgX · Mar 18, 2017

Do you see/feel a recess in the underlying part at that stop position?

Otherwise you may still have to calibrate the exact position. I'm guessing though as I never disassembled a Rodagon.

Hilo · Mar 19, 2017

I have the Rodagon-G 50mm, but I am not near my darkroom now. Will check later to find out if my lens has the same screw and if yes, what it does . . .

Why don't you ask Rodenstock? This is their email for repair questions in Europe: dieter.wenzel@excelitas.com
I got it from their site http://www.rodenstock-photo.com/de/service-support#reparatur. They will be able to reply in English, or refer you to someone elsewhere . . . I would include the same photo you show here.

Since you have trouble changing the aperture, I assume the screw fastens the ring in a specific position and now it is no longer in the correct place

Marco Buonocore · Mar 19, 2017

Thank you Hilo, that's a good dose of common sense. My track record with repairing lenses or cameras is pretty poor! It's a nice lens, and I don't want to damage it. Speaking to Rodenstock is the smart thing to do.

Hilo · Mar 19, 2017

No screw on the 50mm Rodagon-G !
Let us know what response you get from Rodenstock - I am curious !

John Koehrer · Mar 19, 2017

The screw fits into a hole linking the ring to the internal aperture ring.
It is a custom screw because it has a post extending from the bottom of it.
The screw in my old timey 135/5.6 goes like this.......
Diameter=~1.5mm, threaded portion = 4mm and the post = 2mm

Hilo · Mar 21, 2017

John, even if it is not about my lens: nice information you could give there! I guess you unscrewed this screw.

So, the owner should have no problem to find the right position for the external ring?

John Koehrer · Mar 21, 2017

Hilo.
Yup took it out. I have the technology.
There's only one hole in the internal ring so shouldn't be a problem.

Marco Buonocore · Mar 27, 2017

John Koehrer said:
The screw fits into a hole linking the ring to the internal aperture ring.
It is a custom screw because it has a post extending from the bottom of it.
The screw in my old timey 135/5.6 goes like this.......
Diameter=~1.5mm, threaded portion = 4mm and the post = 2mm

Hello John,

I missed your post describing the screw that was missing. Thank you! Your information sounds similar to what another gentleman told me, which was: "...it had a screw head on the outside, it was a long, unthreaded shaft that fits into a hole in the cam plate of the iris unit."

My question now is, where do I get a screw like this? One single screw! I've written Rodenstock a few times, and have had not heard anything back. In Canada, Amplis used to be the Rodenstock distributor, but they no longer service lenses. Their helpful rep told me to "check Google." Brilliant advice.

Does anyone have any ideas where to source oddball parts like this? Or perhaps where I could send an enlarger lens to have it fixed?

AgX · Mar 27, 2017

If you are handy you can make it yourself, either by hand or with some common appliance.

Of course you first have to get you a basic M 1.5 screw first.

Hilo · Mar 28, 2017

I can't understand why you do not hear from Rodenstock, maybe they're all busy searching for your screw!

If they no longer have this screw, they could at least tell you. After that you make it yourself, or have it made. You can ask John to give you a picture of the screw, and its dimensions . . .

Best would be if someone in Germany could give them a call:

Haben Sie Fragen zu Reparaturen von Rodenstock Objektiven:

Ihre Ansprechpartner:

Dieter Wenzel
Tel.: +49 89 255458 183
Mobil: +49 172 8211848
E-mail: dieter.wenzel@excelitas.com

Marco Buonocore · Apr 11, 2017

An update: I eventually was able to speak with Mr. Wenzel, the gentleman in charge of Rodenstock lens repairs. He was kind enough to send me two small screws for the lens in the mail. They were exactly as described by John Koehrer above.

It is a beautiful lens, quite one-of-a-kind in it's ability to make large magnification prints, and I am excited to get it back into use.

Thanks to everyone for their advice, and ideas.

M Carter · Apr 11, 2017

Rodagon G - that's pretty much a Unicorn lens. I want a 150 myself...

Screw missing on enlarging lens

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