pinched optics 130EDT
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Chris Cook
Does anyone know how much of a turn of the front retaining ring is necessary to alleviate pinched optics? I was star testing my 1992 130EDT at 234x this evening and noticed the diffraction pattern both inside and outside of focus is ever so slightly triangular. The scope sits outside in my observatory so cool down is not an issue.
Any help is appreciated.
Chris
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Roland Christen
Back it off as much as you want. The lens is a one piece construction and the retaining ring is just there to keep the lens from falling out if you turn the scope upside down. If that doesn't fix it, it may require service here. Contact George for a return authorization.
Rolando
-----Original Message-----
From: Chris Cook <chris@...> To: AP-UG <main@ap-ug.groups.io> Sent: Mon, Nov 28, 2022 8:30 pm Subject: [ap-ug] pinched optics 130EDT Does anyone know how much of a turn of the front retaining ring is necessary to alleviate pinched optics? I was star testing my 1992 130EDT at 234x this evening and noticed the diffraction pattern both inside and outside of focus is ever so slightly triangular. The scope sits outside in my observatory so cool down is not an issue.
Any help is appreciated.
Chris
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Chris Cook
Ok, I'll give it a try. Thanks.
Chris
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Chris Cook
Rolando,
I tried to loosen the retaining ring but it wouldn't move. I applied quite a bit of CCW rotational force but didn't want to continue in fear of the spanner wrench slipping and scratching the objective. Here are pics of the two holes on the ring and the wrench I am using. There was a very very small amount of black caulking type material in the the gap between the ring and the lens cell near the two holes. Almost like the ring was locked in place. Is this supposed to be like this? Chris    
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Roland Christen
If you can't make it work, then let George know and he will issue a return authorization.
Roland
-----Original Message-----
From: Chris Cook <chris@...> To: main@ap-ug.groups.io Sent: Tue, Nov 29, 2022 12:56 pm Subject: Re: [ap-ug] pinched optics 130EDT Rolando,
I tried to loosen the retaining ring but it wouldn't move. I applied quite a bit of CCW rotational force but didn't want to continue in fear of the spanner wrench slipping and scratching the objective. Here are pics of the two holes on the ring and the wrench I am using. There was a very very small amount of black caulking type material in the the gap between the ring and the lens cell near the two holes. Almost like the ring was locked in place. Is this supposed to be like this? Chris   
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Pete Lardizabal
Any perimeter small set screws on that vintage scope? Pete On Nov 29, 2022, at 2:23 PM, Roland Christen via groups.io <chris1011@...> wrote:
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Chris Cook
I don't see any set screws.
Chris
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ROBERT WYNNE
I think you will find application of dry heat to the retaining ring a possible solution. The ring will expand a great deal faster than its counterpart. If there is some sort of adhesive freezing the retaining ring that really is a problem best handled at A-P. -Best, Robert
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ROBERT WYNNE
Shouldn't force be applied CW allowing the ring to move away from the front element? May the force be with you. -Best, Robert
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Chris Cook
Doesn't CCW (left) loosen? Unless Rolando reversed the threads?
Chris
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George
CCW it is…
Regards,
George
George Whitney Astro-Physics, Inc. Phone: 815-222-6538 (direct line) Phone: 815-282-1513 (office) Email: george@... Video Tutorials: https://www.youtube.com/astrophysicscorp
From: main@ap-ug.groups.io <main@ap-ug.groups.io>
On Behalf Of Chris Cook
Sent: Wednesday, November 30, 2022 11:10 AM To: main@ap-ug.groups.io Subject: Re: [ap-ug] pinched optics 130EDT
Doesn't CCW (left) loosen? Unless Rolando reversed the threads?
Chris
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ROBERT WYNNE
Suppose it depends on whether one views the scope from the front or the back? -Best, Robert
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