Two 150mm lenses...which to keep?

naturephoto1 said:

Donald,

As I recall, the Symmar S lenses, which were a replacement and improvement for the older convertible Symmars, were not intended to be used in convertible form. However, I believe that the Symmar, Symmar S, and the Sironar N lenses are all f5.6 6 element in 4 group Plasmat designs. If you are correct about the ability for the Symmar S to be used as a convertible lens, then why would the Sironar N also not function in the same manner?

Rich

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If they're all Plasmats, then they can all be "converted", though there are certainly enough variations available in the design that some plasmats will work better than others without the front group. My Componon doesn't seem significantly worse with the front group off, certainly no worse than cropping to get the same view -- and it's an enlarger lens.

I can only plead that I'm not familiar enough with a wide enough variety of LF lenses to know the Sironar N is a plastmat type also...