Re: AP1100 autoguiding

Christopher Erickson

Just for general FYI, RCOS OTA's have terrible secondary mirror-based focusers that are notorious for going berserk and slamming into one extreme of the focus range and then jamming. Best fix is adding a Moonlight Crayford and stop using the secondary-based focus mechanism.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Thu, May 19, 2022, 8:29 AM Kent Kirkley via <> wrote:
I hope the "RC" is one of the great ones; ie. An RCOS which were/are incredibly stable.
RCOS' motto was "Focus and forget it", as well a no optical flexure issues.
If a Chinese RC, you probably won't experience this.
Kent Kirkley

-----Original Message-----
From: Steven Panish <scpanish1@...>
Sent: Thu, May 19, 2022 1:06 pm
Subject: Re: [ap-gto] AP1100 autoguiding

Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J

Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.

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