Quote Originally Posted by sanking
1972 sounds right to me. Arthur Kramer published an article in Popular Photograhy sometime around that time (72-74) about the change from the convertible to non-convertible status.

Just for the record, the Symmar-S can also be used as a convertible lens, though the single element may not be quite as well corrected as the two elements combined. One of the reasons that Schneider cited for changing to a non-convertible design was that not having to worry about the corrections of the single elements gave them greater freedom to correct the combined elements.

From the little bit I've read, I was under the impression that the Symmar-S was actually just as good as an older Symmar when converted, but by the 1970's convertible lenses were out of fashion, and even distrusted by some, so the change was really more a marketing decision than an optical one.

The 150 I just got is certainly a nice sharp lens!

I also have a 150mm Xenar lens that originally came with my camera, I have the factory setup focusing cam for it, and the factory set infinity stops for it don't work for the Symmar . I can either mount the Symmar with a few shims behind it (I'll need about 2.5mm of extension to be able to use the infinity stops, (and the lens does seem to focus correctly with the Xenar's focusing cam)
or I can just keep it mounted on the board it's currently one, and not even worry about using it with the rangefinder, as I have the Xenar for that. Would mounting the Symmar 2.5mm in front of the lensboard mess up movements, or is that not enough to worry about? Would I be better off moving the infinity stops, then mounting the Xenar into a recessed board (If I could find one with only a 2.5mm recess)?

Other than the larger image circle of the Symmar, are there any other advantages to it over a Xenar? Sorry for all the questions, and thanks for all the answers!