WRAY 4 1/4 INCH THREAD QUERY

Does anyone know what is the "filter thread" on the front cell of a Wray f4.5, 4 1/4 inch Supar lens?

Yes, I know it is predominantly an enlarging lens, but it gives good coverage on a 4x5 camera.

Unfortunately I do not have any equipment or bits and pieces to determine what the thread is, or might be.
Using a vernier, [measuring the gap with a rule since the vernier scale is useless]. the 'root diameter' seems to be slightly less than 35mm.

I know 37mm step-up rings are available, but apparently not 36mm step-up rings.

regards
Tony

Measuring a 49mm Filter with a vernier the thread OD is 49mm, a Pentax lens that takes 49mm filter thread measures 48.5mm ID. I have a 30mm to 37mm stepping ring the ID is 36.37 which would be the same a lens taking a 37mm filter, the OD of the 37mm to 40mm is 36.9mm

Part of the problem is Britain wasn't metric at that stage so it's highly unlikely it's a modern metric filter thread anyway, it could be something like 1 3/8". My Wray Lustrar looks like it takes a 44mm filter but it's more likely a 1 5/8" filter thread.

I checked my 1950s Ensign 820's lens but the Ross 105mm f3.8Xpres doesn't have a filter thread, back in the 50's a lot of push on filters were used. So make yourself a push on filter holder.

Ian