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Sliced Bread

PostPosted: Mon Mar 18, 2019 8:22 pm
by Nightspore
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In January 2018 I bought a Sky-Watcher ST102 and immediately replaced the stock focuser with a TS Optics (GSO) two-speed Crayford rail. I didn’t get to use it much in 2018 as the weather was weird and I originally used it with my Vixen Porta II/SXG tripod combination. This is heavy for me to carry as I am physically disabled. I discovered that the modified ST102 balances really well on my lighter, more portable AZ5 mount. The similarly modified ST80 always seemed focuser heavy to me so was predominantly used with 1.25” accessories. I never utilised the focuser rotating feature with either the ST80 or the ST102. As I’ve predominantly been using a 2” diagonal with the ST102 I’ve been experimenting with rotating the focuser. It’s not quite as smooth as the rotating focuser on my 102mm Altair Starwave but it is equally effective. I’m starting to think it’s the best thing since sliced bread.

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https://www.teleskop-express.de/shop/product_info.php/info/p3945_MONORAIL-2--Refractor-focuser---e-g--for-Skywatcher-96mm-flange.html

Re: Sliced Bread

PostPosted: Mon Mar 18, 2019 8:58 pm
by Nightspore
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The advantages of rotating the entire focuser for me are pretty straightforward. As I'm partially paralysed the chances of a heavy (and potentially expensive) diagonal/eyepiece combination falling out of the focuser tube as I'm trying to re-position it are probably higher than most.

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What I didn't realise was that the finder rotates with the focuser. This makes adjustments while seated easier and requires less advanced yoga techniques to sight with the finder itself.

Re: Sliced Bread

PostPosted: Mon Mar 18, 2019 9:08 pm
by Nightspore
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It hasn't all been plain sailing with the ST102 modification though.

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Changing the focuser drastically shortened the overall length of the ST102 by about 35mm.

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I tried various length extension tubes until I discovered a 35mm tube basically solved most focusing problems.

Re: Sliced Bread

PostPosted: Mon Mar 18, 2019 9:16 pm
by Nightspore
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Oddly, the APM Amici prism diagonal shown above doesn't need an extension tube in the ST102 and every eyepiece I've tried in it achieves focus.