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Help me get my Coronado PST back together

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#1 bikerdib

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Posted 16 April 2018 - 10:06 AM

I went out this last Sunday and did a little observing with my PST. I bought the little scope second hand almost a year ago. Of course there is not a lot of surface activity going on these days but there was a little flare on the limb.

 

I was having a little trouble getting the image focused so I decided to take the side cover off to check the prism. Yep, it is tilted slightly. I twisted it a little beyond the correct angle and blocked it with some tissue for a few hours to see if it would correct without having to remove and re-glue (I've read here that others have had luck pushing it back into position without re-gluing).

 

While apart, I took a look at the TIF but couldn't really tell if it was starting to rust or not so I separated the eyepiece holder to get at the retaining ring. I made a little metal tool, removed the retaining ring and tilted the scope so the filter would drop out. It hasn't started to rust (yet?), I even held it up to a bright light and looked through it and it looks clear out to the edges.

 

Now my problem, I'm not sure which way it needs to go back in. How do I know which side faces the prism? Or does it really even matter. Looking at the filter, both sides seem reflective. There is a ring around the filter that laps over on one side. Attached are pics of both sides, can someone help please.

Attached Thumbnails

  • 2018-04-16 09.33.07.jpg
  • 2018-04-16 09.32.52.jpg


#2 Joe1950

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Posted 16 April 2018 - 10:53 AM

I found a couple old pix, but I can't tell which side is which from them.

 

IMG_1685.JPG

 

IMG_1688.JPG

 

But, if no one can say for sure, I'd put the retaining ring against the side with more metal and give it a try. It may not matter.

 

I don't have it with me, it belongs to my son, or I'd check it out.

 

 

joe


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#3 bikerdib

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Posted 16 April 2018 - 11:07 AM

Thanks Joe.  I'm thinking that the side with more of a ring covering the lens, like you said, should face the threaded retaining ring.  If it were inserted the other side facing out, the threaded metal retaining ring could possibly chip the edge of the glass.


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#4 Joe1950

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Posted 16 April 2018 - 11:14 AM

Exactly!


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