On Tue, 02 May 2006 16:37:57 -0500, starburst <nope@xxxxxxxxxx> wrote:
>> Start splitting equal doubles from 0.7" down to 0.4". If it never fails
>> splitting them then your scope is OK.
>Caution on this, though. Make sure that the night you choose to do the
>check has really good seeing. Poor seeing will make it appear that a
>decent mirror is a piece of junk, so be careful.
Also, a real piece of junk may be able to split close doubles very
nicely. That isn't a reliable single test for quality. If I were using
doubles for evaluation, I'd compare the ability to split them in the
center of the field to further out. Lots of bad optics will perform well
along the optical axis.
I think it is better to consider a double star test as a method of
rejecting optics. A scope that can't split close doubles under good
conditions is bad, even if one that can isn't necessarily good.
Chris L Peterson