I just took delivery of a Caltar II-N MC 90mm f/6.8 lens, this is the same as the Rodenstock Grandagon II MC 90mm f/6.8. The front element is 67mm filter size. The rear element is approximately 58mm and it is not threaded for a filter.
The Calumet website gives the filter size for the front element. It unfortunately, does not give the size of the rear element.
The lens did not come with lens caps. Does anyone here know the correct size slip on lens cap I should be looking for?