Quote:
Originally Posted by Emanuele
Thanks Peter!
but ARGGGGH!!!!
What do you mean by spherical error? Should I be worried?
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Depends how much error and how much the 'scope cost.
Easy enough to star test.
Out of focus stars should look the same either side of focus.
If you see a sharp outer edge on the out-of-focus disk on one side focus
and a very soft outer edge on the other side...then spherical error is the likely cause.
This link may help
http://www.atscope.com.au/BRO/tutori...ricalerror.jpg