4 replies to this topic

[ahcastvc]

Last week it was time to take the mirrors out and clean them. The primary was really dirty from about a years worth of use outside. I also decided to replace the primary mirror's center spot. The scope is an Orion 8" f/3.9.

 

I used a Rigel WiFiAline to get the secondary situated under the focuser. Then used a Farpoint 2" Laser and a Farpoint 2" Cheshire. 

 

The weather here in north San Diego county has been terrible since I did this so I haven't had a chance to see if it is better or worse than before the cleaning. So any comments are welcome.

 

Thanks!

Attached Thumbnails

• 

[j21blackjack]

Looks about perfect, might want to look into a primary mirror mask to hide those mirror clips, they'll probably cause some shadows and extra diffraction on brighter stars.

[ngc7319_20]

That looks very close.  Testing on a real star is the ultimate test.

[Vic Menard]

It looks near perfect* to me, but the proof is in the image performance. For visual use, verification using a star alignment should tell you how "perfect" your tool alignment actually is (I recommend Mike Lockwood's method  https://www.loptics..../starshape.html  ) For imaging use, well, that can open a bit of a Pandora's Box, especially with full frame chips and tiny pixels...

 

*All circles are concentric except the violet circle (reflected edge of the secondary mirror) which is offset toward the primary mirror end of the tube assembly.

Attached Thumbnails

• 

Edited by Vic Menard, 08 March 2025 - 07:16 PM.

[ahcastvc]

Had a couple of nights of clear skies last week. What a difference both visually and through the camera. Did not have to do any other adjustments!! With the Paracorr 2 all of the stars are nice and round pinpoints. Now all I have to do is to find a new focuser.