#32
Post
by apochronaut » Wed Feb 26, 2020 6:59 pm
Semi-apochromats are usually what used to be called fluorites. Natural fluorite crystals used to be the source of the low dispersion glass, needed. For some years, other synthetic glass has been developed that mimics fluorite's capability , although some companies such as Canon grow synthetic fluorite crystals.
Fluorites are usually somewhere between an achromat and an apo in colour correction, although some are surprisingly good .
Leica lists Fluotars, which are their old proprietary name for their fluorite objectives as well as Pl S-Apos. This follows along the path that Reichert took way back in the 1980's, where they had a parallel line of objectives, Plan Apos and then Plan Fluor Apos. There is a difference in them, noticeable but subtle. I'm not surre what the cost breakdown was on them when new. I've always figured that Leica used tweaked Reichert formulas for that class of objectives, because they were better than their Fluotar formulas. A similar Reichert one would be about 150.00 used. Actually, a Reichert Plan Apo would be not much more + 25.00 for adapters or so.
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