Off-axis guider

Hi All,
I was just wondering has any of yee used an off-axis guider when taking astro-graphs.

Dave, what exactly is an 'off-axis' guider, do you use a small scope to guide? I'm going to get an autoguider when funds allow, but don't really know where to start yet :roll:

Keith..

An OAG is a device that sits between camera and scope. It is a bit like a diagonal in that it splits some of the light (about 5%) away from the camera and into another eyepiece holder at 90 degrees from the original eyepiece. You can then either use an illuminate reticle eyepiece or something like the LPI or webcam to guide the scope.

The alternative is a small guide scope, placed rather like your finder though with a higher magnification, into which you can put your reticle eyepiece or guide camera.

It's a matter of choice really. I have an old "toy" 2.5 inch refractor that I think might make a good guide scope. Currently in my parents' home I shall get a hold of it one day. I also intend getting a Meade OAG which can be seen here...

www.telescopehouse.co.uk/page.aspx?theLa...FvJju&action=lnk

Of course, I will post results here.

Keith, James described prety well what it is..

James, I was thinking about auto-guiding, but it can be abit hit and miss when it comes to working perfectly.
The way I see it, I'll put a webcam in the OAG and using the monitor and joystick, I'll manually move the scope to keep it on track.
Using astrosnap, you can place crosshairs on the screen to keep everything tracked.
It's real micro-management, but it works.
I dont really want to permanently piggyback a scope on the main scope.

I'm currently using GuideDog with the LPI at prime focus and my camera piggy-backed on the scope. I need more practice with manual corrections as sometimes I can lose the star and it takes three or four seconds to get the star back into the crosshairs.

If the LPI/DSI software wasn't so unstable I would be happy to use that instead.

Dave, James, I'll probably get an illuminated reticle eyepiece to start off, but yes, it's a matter of personal choice...just once the end result is the same - very well tracked astrophotos!

Keith..