Adding additional lenses to a Protar set

Hi everyone,

Suppose I were to buy either a Zeiss or a B&L Protar VII set made up of a 290mm & a 350 mm in a compound shutter. Say then I also saw for sale a 410mm lens.
How would I know that the threads on this new lens would match? :confused:

Alan Davenport

I don't think you will know without trying it. I haven't done this on a Protar, but I have added lenses to my Turner Reich Triple Convertible set.