Convertable Sironars

[Ed Balko]

I was aware that the Scheider Symmar lenses can be used at two focal lengths and read in a different thread here that a Rodenstock Sironar and also be converted by removing the rear element group.

Is this true of all Sironars or only certain models?

[Pete Andrews]

If the lens has two focal lengths marked on it, and two aperture scales, then it's convertible.Most of the plain vanilla Symmars and Sironars produced up to about 1970 were convertible.Around that time, both Rodenstock and Schneider recomputed their lens designs, and both the Symmar and Sironar (AKA Sinaron) were improved. It was decided that the convertible feature was to be dropped, in favour of a slightly improved performance, and the lenses gained a suffix letter to become the Symmar-s and Siranon-N. (If memory serves. Doubtless someone will correct me if I'm wrong about the dates or nomenclature.)