Re: AT10RC on a Mach One


Always be flexible and adaptable in your thinking.

Steve E
From: []
Sent: Thursday, August 20, 2015 3:25 PM
Subject: RE: [ap-gto] AT10RC on a Mach One

Sounds like a focuser used on the rear cell instead of moving the secondary
to focus. Problem is using up precious back focus for the imaging train. But
then collimation shouldn't change just by focusing unless the mirrors aren't
held firmly in place. If there is that much mirror shift then there are
other problems as well. There was a SCT at Kitt Peak that lost collimation
just crossing the meridian and needed collimation. That's just poor
mechanically design or craftsmanship. There is mirror shift in all mirror
moving designs as I'm told but the amount is what is critical.


-----Original Message-----
From: []
Sent: Thursday, August 20, 2015 8:07 AM
Subject: Re: [ap-gto] AT10RC on a Mach One

What is an "outside focuser"?

On Aug 19, 2015, at 4:19 PM, Steven Elliott [ap-gto]

I use an RC with an outside focuser and CCD Inspector - easy to collimate,
and very very very accurate - and since focus outside means it stays in
collimation forever - unless I move it.

Steve E
Ned Smith

N 34,53,38.13
W 85,28,17.10
Near Chattanooga, TN



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