Filter size for Rodenstock 240mm f9, old version

[Valentin Trandafir]

Hello, everyone!

I just bought a lens Rodenstock Apo Ronar 240mm, f9. Old version, corrected for short distance photos.
I like to use filters on my lenses.
I serched online and I found that the filter size should be 43mm. But I have a step-up ring 43-77mm and it doesn't fit the filter thread: it has the (almost...) same outer diameter as the lens.
So, my question is: does anyone know what is the filter thread for this lens? Maybe 42mm? Or 42,5mm? Or smaller?

Regards,
Valentin

 

[loccdor]

Can we see a side view of the lens while you try it fit the ring?

 

[Valentin Trandafir]

This is a picture made when Trying to fit a step-up ring

Can we see a side view of the lens while you try it fit the ring?

 

[Valentin Trandafir]

Can we see a side view of the lens while you try it fit the ring?

 

[Valentin Trandafir]

I found the information.
I attach all the specs of all Ronar lenses

 

[loccdor]

Oh, 40.5mm, yes that's what my Jupiter-8 lens uses. Adapters are available. Glad you found it.

 

[Valentin Trandafir]

Oh, 40.5mm, yes that's what my Jupiter-8 lens uses. Adapters are available. Glad you found it.

Thanks!