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Author Topic: The Alternative to the A80  (Read 1229 times)

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Offline NickH

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The Alternative to the A80
« on: 10:20:26, 04 September, 2009 »
Skywatcher Evostar 80

Cheap as chips, same focal length, same OD, (F11.25), and on an EQ mount with tracking, under £200 (way under typically on the tracking mount for around £178. For the 90mm ERF, the Evostar 90 should also work (F10), both will obviously need a tube chop to get the <200mm back focus (Ken, any comments?)

NOt personally tested it, but...I know someone using the old SW909 and getting staggering results..

http://www.bcsatellite.net/bao/sun25jun.html




Thought I would mention it. Evostar 90 is £139 on a mount... sell the mount (£30)..job done




Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

Offline Merlin66

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Re: The Alternative to the A80
« Reply #1 on: 10:46:49, 04 September, 2009 »
Nick,
Sounds good! The key success factors are: MINIMUM f10 focal ratio and the etalon 200mm inside prime focus.

I've also found that when the focuser unit is removed from the Vixen tube the distance from the objective to the rear of the tube is almost the correct distance INSIDE focus for the PST etalon!!
As the position of the etalon NEVER has to move ( relative to the objective) a suitable spacer block with a central 2" hole ( to hold the PST nosepiece) made from 25 or 32mm customwood ( or equivalent!) fitted to the inside rear of the tube should give good results.
- This is being "trialed" as we speak with the latest mod in Oz. Keep you posted.
( It also allows you to possibly re-use the focuser when upgrading to the BF "final solution"........)
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline NickH

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Re: The Alternative to the A80
« Reply #2 on: 10:59:40, 04 September, 2009 »
BF30 is the final solution...on a 7" Maksutov with a 180mm ERF... :-)

That would literally p**s anything out of the water

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

 

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