[ATM] additional lurie-houghton degrees of freedom

[Bob May]

That is what I'm seeing also with the 12.5" one that Dale Horn is
doing.  R1/3 need to be close to each other and very close to the
design spec as they seem to affect the color focus a lot.  R2/4
seem to be quite tolerant and the biggest thing that they seem to
affect is the focus point.  Wonder why that is other than the
first set is rather curved while the second set isn't.  You want
to get the first set of R to within .1% of the ROC and match them
to a few rings for best results.
Bob May
bobmay at nethere.com
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