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Equipment Discussions >> ATM, Optics and DIY Forum

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gerfmon
member
***

Reged: 07/19/12

Loc: Longmont, CO
Unitron Objective Question
      #5629176 - 01/18/13 12:15 AM

Hi all, I recently picked up a Unitron 60mm objective in mount. I'm in the process of building a scope around it. Question is, the three screws that hold the front ring down on the objective, how tight should they be? As I received it, all three screws are slightly lose and the crown and flint have a slight rattle when the cell is shaken.

Unitron used a dab of red paint on each screw, I'm going to assume to "glue" the screws in place. At some point the screws were turned and the paint is broken. As it stands it won't take much vibration for the screws to start falling out.

Thanks for any input.


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ccaissie
professor emeritus


Reged: 09/13/10

Loc: Whitefield, Maine
Re: Unitron Objective Question new [Re: gerfmon]
      #5629502 - 01/18/13 08:59 AM

Maybe somebody disassembled it for cleaning. I helped a friend sort out a Unitron 60 that showed bad spherical abberation. We reversed the components and solved it. I don't remember exactly the "specs" used to reassemble it, but I'd say that components need to be NOT PINCHED. So snug up the screws until the rattle is 95% gone, and put some glue on the threads...like household glue or even wood/paper glue, something to gum it up.

After assembly, I'd check that the shims (I think there are some on these lenses) are where they should be. Then do a star test (glint of sun on a distant shiny thing) at the highest power to prove that nothing is pinched. Images in/out of focus should be concentric and round. The scope does work otherwise right?


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gerfmon
member
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Reged: 07/19/12

Loc: Longmont, CO
Re: Unitron Objective Question new [Re: ccaissie]
      #5631557 - 01/19/13 01:13 PM

Thanks for the advice. I went ahead and snugged the screws just to the point of a tiny bit of rattle left in the objective. Instead of glue I decided to stick with the Unitron style and dabbed a little bit of red paint on the screw heads to hold them in place.

My ultimate goal is to keep collecting Unitron parts until I have at least a full Unitron OTA. But yesterday I cobbled together a full 60mm scope using misc. parts I have lying around. First light last night was excellent, much better than I expected out of a little 60mm refractor telescope! Nice round diffraction rings either side of focus. M42 looked nice, with even a hint of green color. The trapezium was resolved easily. The core of M31 was a nice diffuse glow. Polaris was a easy split, but the companion star was very, very dim from my light polluted suburban back yard. No, it can't compete with my 102mm f/13 refractor, but it sure is a lot lighter to carry around!

Again, thanks for your input.


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ccaissie
professor emeritus


Reged: 09/13/10

Loc: Whitefield, Maine
Re: Unitron Objective Question new [Re: gerfmon]
      #5635309 - 01/21/13 04:35 PM

Success! I'd also like to collect Unitron parts....I've got an equatorial head that I put my instruments on, currently my 6" f/10 Newtonian. It probably came from a 5", and maybe I'll check the numbers. People want to buy the mount, but where will I get another as good?

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