Mistery flange.

[Marco Gilardetti]

I have recently purchased a large format lens, and together with it came this flange, which apparently has nothing to do with the lens itself. There is nothing, nor in the front element, nor in the rear, nor in the shutter body, that fits this flange inward or outward.

Can anyone perhaps understand to what does this flange belong to? To give an idea of its size, it is a bit smaller than a Copal 3 shutter body, but as said nothing fits to it. As can be seen in picture, the outer edge is milled, and it's threaded on the bottom. The inner circle is instead smooth, with no threads.

I'm refraining from disposing of it, as perhaps someone else needs one of these...

Dead Link Removed

Dead Link Removed

 

[AgX]

Giving us precise dimensions might help. Though its shape does not make a bell ring for me.

 

[Ces1um]

It's a giant pinhole lens.

 

[jim10219]

It's a DIY IR filter kit. You glue fully exposed and developed slide film sheets into the back of the ring to make an IR pass filter.

No wait! It's a lens cap adapter ring. It allows you to use a smaller, pinch style lens cap with your bigger lenses.

Nevermind. It's vignetter. You screw it on to get that classy vignette look in the corners.

 

[EdSawyer]

It's likely a Copal-3 mounting plate for the extension tubes for lenses, usually sold with a Linhof technika board. Ebay has listings for them regularly. Basically a series of threaded tubes, with different plates that can mount various shutters on the front of the tubes. Particularly handy for mounting long lenses on cameras without a ton of bellows.

 

[AgX]

If it is a ring-screw to mount an extention tube to a lensboard, why then is the inner diameter less than that of the thread tubing?
Am I that slow on the uptake again?

 

[John Koehrer]

Any of the above or a series size retaining ring or................?

 

[shutterfinger]

Series VIII or IX retaining ring.
https://www.apotelyt.com/photo-accessory/series-filters

 

[Marco Gilardetti]

Thanks to all those who suggested the series filters. I didn't knew of their existence and it has been an interesting reading. However, I couldn't find any ring with the same layout as this one.

It may indeed be the top cap of an extended lensboard. In this picture, flanges that look similar to this are displayed:

I have excluded it at first, as a Copal 3 doens't fit the hole. I remember that somebody suggested it may fit a "Copal 3S": I read his reply yesterday but for some reason I can't see it anymore today. Has the post been deleted, perhaps? Hwoever, once again I didn't even know that such a thing as a "Copal 3S" existed. SKGrimes reports some figures, I will check and see if perhaps it's indeed a flange for 3S shutters:

http://www.skgrimes.com/products/new-copal-shutters/standardcopals

 

[Old-N-Feeble]

I deleted my post because I thought it was of little or no help. A Copal 3s requires a very slightly smaller hole than a regular Copal 3.