Re: [APML] SCT mirror lock

["Steve Walters" <swalters@att.net>]

I have found that my 12" Meade SCT will exhibit a lot of mirror shift after
it sits for a month or so. But if I crank the focuser to the far ends of its
travel in both directions a few times, the system shows virtually zero
mirror shift when focusing. This is at 200x. I believe Doc G on MAPUG
claimed that doing this re-distributes the grease on the baffle tube. I do
know that it really fixes my problems although it takes 3 or 4 minutes of
continuous cranking the focuser knob to do this. It's a bit exhausting but
it really makes a big difference.

I am not saying this eliminates mirror shift all together. I still use an
OAG for photography. But I have tried various lockdowns and convinced myself
that they don't do much for the shifting. And, if you forget it's locked,
you could be in for an expensive repair. It's something else to remember to
do/undo. At 3 am in 14 deg weather, my IQ drops about 70 points. So I
decided against using these gizmos.

A minority view, no doubt.......YMMV.....

Steve...

swalters@att.net
http://astrophoto.home.att.net


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