Nexstar 8i - Guide Scope

ausmensan (Simon) · #1 23-01-2008, 04:53 PM

Hi there,

I want to mount a guide scope on my Nexstar 8i. I already have the GPS module placed on top, so ideally a replacement for the 'red dot' finder would be nice.

Does anyone have any ideas as to what would be the best item to use? Something that fits well, without balance issues, and preferably something inexpensive. I will be using it with PHD and GPUSB.

All ideas welcome.

Thanks

allan gould · #2 23-01-2008, 05:15 PM

If you want a very small scope to use by replacing a red dot finder an 8x50 finder scope modded to take a webcam will do well as PHD is capable of sub pixel guiding. Have seen some setups using this with the eqmod software.

Matty P (Matt) · #3 23-01-2008, 06:02 PM

Hi Simon,

I have a Nexstar 8SE similar to your Nexstar 8i. I am assuming that you have the same mount as my Nexstar, one fork arm. If you do, when adding any accesories to these scopes you have to be aware of how much extra weight you are adding on the mount. If you add too much extra weight there may be some tracking and balancing issues.

I am considering a Orion ShortTube 80 Guide Scope for my Nexstar.

Weight 1340g.
Tube Length: 40cm
Tube Diameter: 92mm

Have a look.
https://www.bintelshop.com.au/welcome.htm

ausmensan (Simon) · #4 23-01-2008, 06:27 PM

Hi Matty,

Yes, the Orion looks fine, just wondering how you planned on mounting it to your Nexstar? There doesn't seem to be too many options on mine, apart from removing the red dot finder.

The C16GPS takes up the top part of the scope, so anything else would require an additional weight apart from the guide scope which I am trying to avoid.

Cheers

Simon

ausmensan (Simon) · #5 23-01-2008, 06:29 PM

Hi Allan,

yes, thanks for the information. I already have the modded webcam ready to fit, it is just the guide scope I am trying to sort out now. The ones on Bintel seem to be for specific scopes. I guess most ones for the Nexstar would sit where the GPS unit is normally, but I'm not 100% on that.

Very impressed with PHD though, nice piece of software for free!

Cheers

Simon

Matty P (Matt) · #6 23-01-2008, 06:46 PM

Quote:

Originally Posted by ausmensan

Hi Matty,

Yes, the Orion looks fine, just wondering how you planned on mounting it to your Nexstar? There doesn't seem to be too many options on mine, apart from removing the red dot finder.

The C16GPS takes up the top part of the scope, so anything else would require an additional weight apart from the guide scope which I am trying to avoid.

Cheers

Simon

I'm not quite sure myself where I would mount a guidescope.

If there is a will, there is a way.

I hope to move the RDF to left and find some mounting brackets for a guidescope.

Have a look at the Cloudy Nights Forum if you haven't already. There is a specific forum just for Nexstar scopes. I have found some very good information there.

http://www.cloudynights.com/ubbthrea.../Board/nexstar

With the GPS unit, Would you be able to place it anywhere other than the top part of you OTA?

Matty P (Matt) · #7 23-01-2008, 09:49 PM

I've been doing a bit of research and found this link.

Piggyback rails for C8
http://www.scopestuff.com/ss_pigy1.htm

I also found that the maximum weight you can safely add on to your scope is roughly around 2.7 - 3kg including any standard diagonals and eyepieces. I could be wrong.

When mounting the guide scope try to put it as close to the arm as possible to make it easier on the mount. Another suggestion, go for a RACI 9X50 finder scope as a guide scope. The reason why I say this is because by the time you add eyepieces camera equipment etc, you'll be over your weight the limit and possibly overload the mount. I still like the idea of the Orion ShortTube 80 as a guide scope.

allan gould · #8 23-01-2008, 11:50 PM

I think this is exactly what you want.
http://eq-mod.sourceforge.net/testimages/
Have a look 1/2 way down the page and you will see Maurce Valimberti's setup which uses a 50mm scope with a modded webcam to guide an ED80 scope. The finder scope would fit where your red dot finder goes.
Hope this helps

ausmensan (Simon) · #9 24-01-2008, 01:05 PM

Hi Allan,

Yes, funnily enough, I saw that link yesterday when browsing around. Very interesting setup, and some pretty good pics also!

Thanks for that.

Simon

ausmensan (Simon) · #10 24-01-2008, 01:07 PM

Hey Matty,

Yes, the weight distribution is a problem, I am trying to avoid any extra rails etc, but maybe that isn't possible. I'm going to have a closer look this weekend and take the red dot finder off. Perhaps I can jury rig something, and use the guide scope from my C10-NGT.

all the best

Simon