Autoguiding and Arcsec/pixel

Say I have a refractor and autoguiding camera which combined would give an imaging scale of 2.3 arcsec/pixel.

Then, I have my SCT which, with the camera I want, would have an imaging scale of 1.65 arcsec/pixel.

In terms of autoguiding, does the guide camera and guide scope have a good enough imaging scale to autoguide the main scope and main camera? If not, what sort of relationship between imaging scales should I be aiming for?

Cheers,

Hi Michael,

The conventional view is that the guide scope can be as little as 50% of the imaging scopes F/L and still get well tracked shots.

Dave Grennan was using at C9 1/4 prime focus guiding through a 600MM 80mm guide scope with no difficulty.

I don't think that image scale is that bigger deal other than using a scale that does not give scinterlation (sp?) a major role. Usually you could bin the guide camera if image scale is below 2 arc secs.

Later,

Jed.

Michael as Jed said, don't get too hung up on it. Most autoguiding software works to sub-pixel accuracy to a very high degree. Remember that you only have to keep within +-2" to ensure sharp round stars. This should be easily acheivable with your setup. Best idea is to suck it and see.

There is really no problem in guiding using a small scope as the Dave and Jed have mentioned. I am using a STV camera that is connected to a Nikon 300mm at f/2.8 camera lens (ie 12 inch focal length); guiding a large telescope with a focal length of 151 inches.

After using Pempro for feedback on PEC the tracking result is excellent. I have achieved 10 minute exposure with good results.

Hope this helps

Eamonn A