Re: ATM An $18.00 Null Test

[Michael Pankratz <papilio1@juno.com>]

Hi Dave,

Nice write-up!  Not sure, but at first glance this would appear to be a
variation of the Dall Null Test, but with the lens in front of the KE
instead of the light source, and with the greater
light-source-to-test-surface distance accounting for part of the null
observed.  Have you done any raytracing analysis to see how the accuracy
of your null compares with Dall's?  

Looks like a very useful test, and it certainly allows the use of a
cheaper lens than does the Ross test.  Thanks for the post!

Cheers,

Michael Pankratz
Tesuque, NM
papilio1@ juno.com
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