Quote:
Originally Posted by AlexN
..... the GSO RC primary is fixed...
Alex.
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OK this may take some effort.....Does the secondary have a central dot?
(usually applied with a permanent marker by kind manufacturers)
If no....then, make a thin cardboard mask with the same diameter as the secondary and put hole in the middle (cardboard..not the mirror
) , put it over the secondary and apply a dot via said hole.
Use a laser collimator to put laser spot over above dot on mirror.
Adjust the secondary to put the spot on the dot. You are almost done.
On a night where you can actually see an airy disk, have a look at a say mag 4 star.
Center it.
Do the diffraction rings look symmetrical?
No? then adjust the secondary to make it so. Remember *tiny* changes (eg Max 1/8th turn)
When the diffraction patterns are as round as you can make them, you are done.
Be happy or buy a better instrument!