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Skywatcher 18" and 20" Truss Dobsonians


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Skywatcher, it would appear, are to introduce two new dobsonian models in the Autumn. An 18" and 20" truss dobsonian that is currently in a prototype stage. The construction will be influenced by Obsession, mirror box / rocker box type design principles, so improving balance, becoming more bottom heavy. This will be in addition to the Flextube's, which will continue production up to 16". Note: the larger models are to be truss and not flextube (three strut pole) versions.

I learnt about this through a conversation, visiting the Wide Screen Centre at the weekend. There is little information on the internet, all I could source was some vague information on Cloudy Nights, indicating that the mirrors may be constructed in a lighter material.

All very interesting though. Anyone else have any additional info to add to this?

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Wonder how big a 20" flextube would be ;)

Depends on the focal ratio :D. A 20" F/30 would be huge.

If true, I welcome these new dobs, I've always thought it was odd that Skywatcher stopped at 16", and that they don't make their dobs light at all.

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Our 20 inch is F4.1. We have a visiting 20 inch F5 on occasion and the difference is very serious! It doesn't much matter for low targets but that ladder can give the faint hearted pause when you're onto something near the zenith!

Olly

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I had a look through a David Lukehurst 20" F/4.2 at the SGL starparty a few years back. The views of M51 and M13 were stupendous but it seemed an absolutely massive scope to me, even in the dark :shocked:

Orion (USA) were listing some huge dobs not so long ago - as large as 50" !. Not sure if any have actually been produced though ?. The relevance is that Synta make lots of Orion stuff as well as Skywatcher and Celestron of course.

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good as it is that bigger dobs are being made..its once again the age old big dob issue of weight,portability and the main one for me is height..stepladders are not fun and the feeling of being 3 feet in the air in the dark with £££'s worth of glass in your hand and around your feet....I went for a 18" F3.9 a perfect height for me,in fact F4 or below is the only way to go when going up in mirror size for me.

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I looked through a 22" f5 once and the eyepiece was 9 foot high at the zenith. not for me. in fact it was a cure for aperture fever. fantastic as it was it was just too big without a large purpose built trailer and a lot more land (and money) than I have. even then I am not a fan of ladders for observing.

I sincerely hope that these large dobs are made of better materials and to a smaller footprint.

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I sincerely hope that these large dobs are made of better materials and to a smaller footprint.

Agreed. :)

I hope they learn that those ridiculously small alt bearings and shoddy balance issues just don't cut it at these sizes. :)

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