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Selsi pickup.... what do I have here?

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#26 Maranatha

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Posted 18 February 2024 - 11:13 PM

Did a quick test by holding a 1.25" eyepiece (or diagonal) over the focuser tube, and I do notice a definite improvement in both eye relief and clarity. Although it's cutting it close in regard to coming into focus ... have a smidge left as far as the focuser tube goes, but not much.

 

As for adapters, any specific ones better than others?

 

I was thinking of just 3D printing one, as my library offers 3D printing ... although not entirely sure which file to choose from (there seems to be a zillion .965 to 1.25 adapter files out there). Also not quite sure how long it takes to print one up ... my library is cheap, but charges by the hour. I'd guess not long at all, but I never had anything 3D printed before.

Late to this thread but was looking up Selsi info. If you want to adapt .965 to 1.25 buy this.

 

https://www.amazon.c...e?ie=UTF8&psc=1



#27 AstroPotamus

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Posted 18 February 2024 - 11:33 PM

I just might have to buy one of those.

#28 SporadicGazer

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Posted 19 February 2024 - 12:08 AM

Late to this thread but was looking up Selsi info. If you want to adapt .965 to 1.25 buy this.

 

https://www.amazon.c...e?ie=UTF8&psc=1

It's cheap enough to try, but it'll only work if you have enough focuser travel to accommodate the extra distance.

 

A better, but far harder to find, option would be a hybrid diagonal.  (Telescope Warehouse has them, but theirs aren't going to win any mechanical robustness awards.  Scope Stuff has one that looks sturdier, but it has a shoulder that adds unnecessary length and might also cause focus problems.  Then there are several Asian vendors on Amazon that sell, what is probably the same unit, that have slow shipping and very mixed reviews.)

 

Last option, I've heard of, is replacing the visual back on the focuser drawtube:

 

https://www.cloudyni...sic-refractors/

 

but which option works with which scope is mind numbing, eye crossing, and apparently uncertain due to vendor changes.



#29 Joe Cepleur

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Posted 19 February 2024 - 06:55 AM

Anony, could you replace the entire draw tube? I'd guess that an inch-and-a-quarter drain pipe from your local hardware store may not fit. I replaced the draw tube on my Royal Astro Tasco 7te-5 to greatly widen the field of view.

This next suggestion involves permanently modifying the telescope and is not guaranteed to help, so consider carefully. Look inside the draw tube. Is there a tight little baffle somewhere near its middle? This would be a (likely) metal disk pressed into place, with a small hole at its center. Its job is to prevent scattered light from wreaking the view. In an expensive telescope, its placement is carefully coordinated with other baffles in the main tube, but in cheap ones it may just be stuffed in there somewhat arbitrarily. In that case, removing it may (or may not!) increase the field of view.

In my Towa Jason 313, tapping the draw tube's baffle out with a dowel dramatically increased the field of view. I then rolled a piece of flocking and stuffed it into the draw tube prevent the scattering of light. ("Flocking" is a material that prevents light from bouncing off surfaces.) Popped on a 0.965"-to-1.25" adapter and have had a great telescope since! (This particular Jason is a rebranding, in cheap livery, of a telescope also available as a more expensive Sears.)

The sticker on your telescope showing that that it was a premium from an investment partnership makes it interesting.


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