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Sharpstar 150HNT - removing correcting lens to collimate?

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3 replies to this topic

#1 Cinnamon

Cinnamon

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Posted 28 February 2024 - 12:54 PM

Hello,

 

I own the 150HNT, and the collimation instructions recommend removing the corrective lens in the focus tube to collimate the scope. It screws into a tube that goes onto the focuser, so you need to unscrew the lens from inside that tube(reassemble and then laser collimate). Mine sits about 6-7 mm below the top of the tube it is recessed into.

Two questions:

1) Is the depth that the corrector screwed into this tube important? If so, I will have to measure it accurately.

2) What is the best way to remove it? I have a spanner wrench, and I have put a decent amount of force on it, any more, and it slips, and I'm terrified of scratching the lens. I gave up trying to remove it and laser-collimate it through the lens, which they don't recommend. 

Any tips on getting that thing out?

Thank you

Scott



#2 dan_h

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Posted 28 February 2024 - 01:26 PM

https://www.bing.com...age&form=rc2idp



#3 Cinnamon

Cinnamon

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Posted 28 February 2024 - 01:36 PM

Thanks, that's a lot better looking spanner wrench than the one I have.



#4 OregonAstronomer

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Posted 28 February 2024 - 02:23 PM

I have the same scope. When I misplaced the tool that came with it as shown in dan_h's picture, I ordered this one from Amazon:

 

https://www.amazon.c...,aps,265&sr=8-3

 

neewer.jpg

 

The position of the corrector lens does matter in order to achieve proper back-focus. If you need to adjust the back-focus by a tiny amount, you can actually do so by screwing the lens in a little farther or backing it out a little.

 

Arnie




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