Question about Fastar

[traveller (Bo)]

I got a surprise when my Nexstar 8SE purchase from the US turned out to be Fastar compatible. From what I can find out form CN and other forums, a few 8SE OTAs had Fastar compatible secondaries installed, but Celestron has since stopped this. I understand the basics of Fastar, turning a f/10 into a f/1.9. I also understand that Hyperstar is the aftermarket equivalent (or better) than the original Fastar. I have a couple of questions that people might be able to help me with:
1. How do you get Fastar/Hyperstar in Aust? Or do I need to turn to the US? Price? I did a search on the archives and didn't get many results.
2. Has anyone got one/used one? What are your impressions? I read (with a good pinch of salt) that the Nexstar Alt-Az mount can be good enough for AP work with a Fastar. Has anyone tried this?
I don't have a dedicated CCD AP camera, just a QuickCam Pro and a SPC 900. My aim of the 8SE is to use it for visuals and a grab and go for camping etc, and then get a GEM mount for AP work later.
But if I can start with basic AP with a Fastar, I might give it a go.

Cheers, Bo

[Merlin66 (Ken)]

Ex -USA
A great idea - f2 on a SCT!
Expensive - yes....
Does it work ....yes
IMHO I'd start with a x0.63 reducer first.....
(The focus tolerance on the Fastar optics is less than 10 micron! and you need a suitable camera etc etc)
Just my 0.02 Euro (after tax)

[frolinmod]

About ten years ago I bought a Fastar lens and played around with it on a C-14. I know they still make and sell Fastar compatible scopes, but does Celestron even make and sell Fastar lenses any more?

The only place I know of that sells Hyperstar lenses is Starizona. I even bought one for my EdgeHD 14. Haven't used it yet. I'm a bad boy.

If your Nexstar 8SE can handle the additional weight of a camera, then it'll probably track just fine for the minute or less it takes to capture images of at least the larger brighter showcase objects in mono or single shot color. A filter wheel may add too much weight. You probably shouldn't even think of going narrow band because of the long exposures needed.

[Merlin66 (Ken)]

No, Celestron don't do the Fastar lenses anymore.....

[Poita (Peter)]

The only option these days is the Starizona Hyperstar. You can get them on their website, and for the C8, it is relatively cheap. USD$695

http://starizona.com/acb/hyperstar/ordering.aspx

Instructions etc. are here:
http://starizona.com/acb/HyperStar-L...-P991C648.aspx

[traveller (Bo)]

Thanks for your responses everyone, much appreciated.

Originally Posted by Merlin66

IMHO I'd start with a x0.63 reducer first.....
(The focus tolerance on the Fastar optics is less than 10 micron! and you need a suitable camera etc etc)
Just my 0.02 Euro (after tax)

Yikes 10 micron!!!???? guess the 0.63 reducer has better torlance? (and therefore the 0.33 reducer somewhere in between??)

Originally Posted by frolinmod

If your Nexstar 8SE can handle the additional weight of a camera, then it'll probably track just fine for the minute or less it takes to capture images of at least the larger brighter showcase objects in mono or single shot color. A filter wheel may add too much weight. You probably shouldn't even think of going narrow band because of the long exposures needed.

I need to get used to visuals on the new scope first and perhaps the 0.63 reducer later one. Fastar/Hyperstar is just a bit too steep on the old learning curve so far.

Originally Posted by Poita

The only option these days is the Starizona Hyperstar. You can get them on their website, and for the C8, it is relatively cheap. USD$695

http://starizona.com/acb/hyperstar/ordering.aspx

Instructions etc. are here:
http://starizona.com/acb/HyperStar-L...-P991C648.aspx

Definitely keep that in mind (and the cost )
Bo

[Merlin66 (Ken)]

The "Critical focus zone" is related to the f ratio
Don Goldman gives delta f = 1.6 fr^2 x Lamda
Where Lamda is wavelength in nm.
Other references (based on 1/4wave tolerance) give slightly different values

Summary
f10 - 220 micron
f8 - 141micron
f5 - 55 micron
f4 - 35 micron

HTH