old C8 with guide?

[Gerhard]

Hi all!

Has anyone had any experience with old Celestron C8s (30+ yo) that can be "manually guided"?

I'm trying to find a way to do this (well, actually my friend who owns the C8 is), and it appears originally there was an option to attach a guide scope with illuminated crosshairs, with a big magnification, which then would show any aberrations of the mount motor. You were then able to adjust the motor velocity by hand with a potentiometer, or something of the kind...

Anyone ever did this? Or something ismilar? Does it make sense to pursue such a solution for this old scope?

Or should we save the money for buying a new setup that would have a million more options, because new...

thanks!

Gerhard.

[michael.h.f.wilkinson]

I have manually guided my GP-C8 using an off-axis guided. It is doable, but tedious. The big advantage of the off-axis guider over a guide scope is that it has a huge magnification, and it shows any deviation caused by flex in the scope itself.

My scope is younger, but still 19 years old.

[Gerhard]

Thanks Michael!

just a quick beginner's question: off-axis guiding, is that when the guide scope points in another direction as the main scope? This, to aim at a bright star that is used for guiding, that is not in the fov of the main scope?

furthermore, how did you adjust the motor of the mount? was it like I described, with some kind of knob to turn to adjust the power to the motor? And therefore having to sit by the scope all the way through the shoot (hence the "tedious")?

ps: I see you're from Groningen!! I'm Dutch, and I used to study at the RUG! :-) Where do you go for observation?

[rowan46]

http://www.jtwastronomy.com/tutorials/autoguider.html

[Peter Drew]

The older versions of the C8 could be coupled to a variable frequency oscillator which provided a small % +/- correction to the drive rate.