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Old 26-11-2013, 07:31 PM
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Peter.M is offline
Join Date: Sep 2011
Location: Adelaide
Posts: 914
Originally Posted by bkm2304 View Post
Hi Peter,

I would suggest you get an off the shelf Celestron Fastar or Starizona Hyperstar modification for those scopes. This converts an F10 to F2 and gives about 25x the field of view.

Have a look here.

I am thinking of creating a newtonian not a SCT.

Originally Posted by Meru View Post
Sounds like a good idea Peter, would be great for widefield shots. I think you'd have to possible alter the secondary (Depending on your CCD size). Not sure if you are aware but Teleskop Express sells off-the-shelf CF upgrades for GSO scopes. They dont come cheap though
Part of the allure is creating something myself, so I wouldn't buy the tube off the shelf.

Originally Posted by Astroman View Post
Can I ask why the scope is in bits?, an 8"f4 should be fine for Adelaide's skies I would think.. although at f2.8 wow thats cutting down the exposure times... Would it be cheaper just getting an ASA scope, or even a SCT with the Hyperstar from Starizona.. Much less hassle to if the reducer doesn't work with the GSO optics.
The scope is in bits because I was trying to track down sources of collimation wandering, and then I ended up building my current scope. The corrector itself is around 1200 an ASA scope while I would love to own one would set me back over 10 grand landed.

Originally Posted by clive milne View Post
Why not just use a bigger chip at f4 and bin the pixels?
The attraction of sticking with the current camera is partly due to cost, but also due to the larger chip requiring a larger secondary mirror and corrector.

Originally Posted by LightningNZ View Post
I've got a friend who has been really struggling to get his Hyperstar producing decent images. It can collect a lot of data really quickly but keeping decent collimation and focus is major PITA.

Unless everything is locked down really hard and you have a great focuser I'd not recommend going much under F/4.0.

Good luck,
I don't think I have seen a decent image produced with a hyper star. The focuser I would be using would be able to use focusmax so I would not have to bugger around doing it, and using carbon fiber should hold it in focus well.

I am less worried about the tight requirements at F3ish and more worried that even in the goldylocks zone the corrector will still not perform as I want it too.
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