Old 19-05-2022, 02:08 PM
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Boozlefoot is offline
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Posts: 320

As the cloud ridden boredom sets in......this is the pointy end of my experimental open long refractor. 74mm f3000 glued achromat, 3 hours with the dremel modifying the objective holder (70mmf500SW OTA), old finder with the lenses removed for a "hood sight". The Skywatcher wedge will hopefully aid in alignment. The "body" will be a simple wooden beam (Guitar tuners & wire for pretensioning) on an AltAz pipe mount, and the focus assembly will be a macro photography mount for coarse focus and a 2" helical for fine mounted on that. Plan on using maybe a 28mm EP. I fully realise the image may not be up to everyone's standards, but this is an experiment (ongoing) after all. I start on the focuser end next week...... And probably not what Skywatcher envisaged.
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Old 24-05-2022, 02:45 PM
gb44 (Glenn)
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What are you aiming for?

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Old 24-05-2022, 03:11 PM

JA is offline
Join Date: Oct 2016
Location: Melbourne, Australia
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Hi BF,

3000mm - Very Long Refractor for sure !!!

Given that you already have the lens cell and front mount you could consider some using 75mm, 80mm or 90mm Stormwater or SWV pipe. The only issue would be painting the inside black. Also if you have the standard focuser from the older donor scope you could also bung that in at the end of the tube, with some adapters which are plentiful and in many designs for typical SWV and stormwater pipes. You could also add a strengthening rib or two if you found it necessary by simply gluing a rib to the outside of the tube.

Good luck with your project.


Last edited by JA; 24-05-2022 at 05:29 PM.
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Old 28-05-2022, 09:25 PM
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Boozlefoot is offline
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Posts: 320
Thanks JA and Glenn.

Find the idea of an open refractor (no tube) will be an interesting project here as I have the fortunate circumstance of an above average dark site, Bortle 2 at the worst.

So - no OTA! The objective holder was from a write-off (busted focuser), seemed the best/lazy way to have a "coarse adjustable" pointy end, and it even comes with a dew shield. The focuser end will now be constructed from a used photographic bellows assembly for the coarse, then an adaptor and 2" helical focuser for fine focus. And nothing in between except the wooden mounting beam.

Probable targets will be moon 1st quarter and planets, expecting 17th century results!

Remember, it's all in good fun and helps while away the time till this cloud eventually shoots through.

And speaking of boredom........there's a windmill tower directly behind my obsy which is begging to become an aerial telescope!
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