Originally Posted by
TAG
I actually read the standard way back when and if I recall correctly, it basically said that apochromatic simply equates to exceptionally good chromatic abberation correction. The standard no longer required that three colors be brought to the same focus for a lens to be designated as apochromatic. This actually makes perfectly good sense, because using modern optical glass, the secondary spectrum of lenses corrected for only two colors can be so small as to be equal to or even less than that of lenses corrected to bring three colors to the same focus as required by the old definition. Schneider seems to think that Apo Symmars have improved chromatic correction over the Symmar-S, but I think it is mostly at the edges of the image circle. I think most people would think that is a good thing.
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