Rodagon f/5.6-80mm Filter Thread Size needed - to reverse mount lens

[oly2b]

Hi All - just purchased a Rodagon f/5.6-80mm Cat No 71.080.01 s/n 9267043 and I gust it would have a filter thread of 40.5mm but it is more like 35.5mm.
I purchase this lens to use on a slide copier rig (Pentax bellow, auto tubes etc) and need a step up ring to get to M42mm of the bellows.
Can any one confirm the filter size,

 

[MattKing]

Welcome to Photrio.
Are you asking about the filter thread (front) size, or the mounting thread (rear) size?
This may help: http://www.prograf.ru/rodenstock/enlarging_en.html#table1

 

[AgX]

In that listing the lens in question is not even listed, not by data, but also not by its age, as it is a lens from the 60'/70'

 

[oly2b]

Yes it is a old lens (wish I went for the more modern f4-80 which would have a 40.5mm filter thread).
The front lens filter thread measures as ID 35.02mm approx. so I can only find M34.5mm filter size used ion some Nikon enlarger lens

 

[AgX]

Why do you need a srew-in connection at all?
To my understanding your issue is to fix the front bellows (light shade) to the front of your lens, and such can be improvised as no strong forces apply as thos bellows and the copying (slide) stage is held by the upfront standard.

 

[AgX]

Alternatively you could glue a more appropriate filter- or adapterring to the the lens.

 

[oly2b]

I want to use it on a slide copying set, where the 80mm lens is used reversed (0.75x reduction) then a macro extension tubes and the Pentax slide copier adapter so the filter thread needs to connect with M42mm of the macro tube.
I have found and ordered a M34 to M49 step up ring (plus other rings to get down to M42).
Yes Threadlock or glue if the M34 is undersized.

 

[AgX]

I see, yes then the connection must be stable, but a well glued ring should work.

One issue here is that there is not much of data sheets for older Rodenstock lenses around.
A means to establish the thread size is to take a female and male filter of same size of nearest size to yours and measure both thread diameters. Add their difference to your ID and you got the thread diameter you need.

 

[MattKing]

I've added a reference to your title to make your need for a reversing ring more clear.

 

[ic-racer]

Sk Grimes inUSA can machine an adapter for you but it may cost more than a different lens with a more common front thread diameter.

 

[MARTIE]

Hi, I think this is what you're looking for; an old style Rodenstock Rodagon 80mm f5.6 fitted perfectly with a B&W 35.5 filter.
Your best bet in the UK, will probably be SRB Photographic. If they don't seem to list what you're after, it doesn't automatically mean they don't have it in stock or that they can't make it. I know they've done bespoke work in the past.
https://www.srb-photographic.co.uk/