Quote:
Originally Posted by bratislav
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Yes, it looks like in far IR FPL53/ZKN7 may get worse, but where it counts (400-800nm) it is far superior.
Bratislav
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I found this 2004 reference from Tom Back, who penned some lines on the nature of the AP155 glass:
"Roland was very fortunate to find a large supply of an abnormal dispersion flint, similar to Schott KzFS-1, but even better in its color correcting properties. In fact, it was ordered by NASA, but was never used. When Roland found that the supply was available for sale, he gladly bought it up. By-the-way, this "NASA" flint glass was the ultimate in short KZ flint glass. No manufacture supplies a flint glass that can match its abnormal dispersion properties today."
As to whether this is still true, I can't say, but given things are driven by cost these days, rather than performance, it probably is.