Quote:
Originally Posted by Paul Haese
Hmm until you start imaging at f3.8 and lower, then they are not parfocal and require offsets. Not much but enough to cause some initial setup time.
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On nights of excellent seeing if I am using say F4.5 I have found you can finesse the focus for each filter if there is a refractive element in the optical system.
.not the filters fault, but simply a teeny sphero-chromatic shift from the optic.
If I'm using just mirrors, then I have yet to detect any focus shift with the Dons.