[APML] focusing with CCD

[Antonio Agnesi <agnesi@ele.unipv.it>]

Hello,
has anyone ever tried the ST4 or STV as a focusing aid? It is quite easy to
make an adapter parfocal to the film plane, calibrate the exact parfocal
length of the adapter against a knife-edge test on the photocamera and
using the CCD for focus optimization. (for best results just stop-down the
scope aperture to increase a little the field depth if the star size is
smaller than the pixel size) This does not require to move the scope much
farther from the target as when searching for a bright star to make
knife-edge each time you change target.
I would be curious to learn about similar tricks.
Thanks and clear skies,


Antonio



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