CGEM periodic error
Posted 26 June 2009 - 12:31 PM
When compared to a less expensive mount, say, an LXD-75,
it seems that the extra money for the CGEM buys more
load capacity, not less periodic error. My LXD-75 seems to
have a comparable amount of periodic error.
I tried PEC, and it did help to get rid of some of the worm error amplitude.
The mount was purchased for imaging as well as visual use.
I was wondering what experiences others might have had with a CGEM mount.
Posted 28 June 2009 - 10:40 PM
I am interested in what others have to say about this also. I have a CG-5 mount and I am considering a CGEM for the extra load capacity.
Hopefully some CGEM owners will chime in.
Posted 29 June 2009 - 01:50 AM
Posted 30 June 2009 - 02:12 AM
I use an Orion auto-guider and I am getting 6 min. plus exposures with round stars in an 8" F/8 Newtonian with my CGEM. Charlie
Same here....my max exposure time autoguiding with PHD and an Orion SSAG is 5 minutes with an F7 105mm refractor, and that is primarily due to limiting light pollution. Round stars and little drift. The Polar alignment routine works well, and it is dumb simple. With good autoguiding, pec becomes much less of in issue in imaging.
Posted 30 June 2009 - 03:22 AM
Without (auto)guiding you'd be hard pressed to get round stars even in widefields with short lenses.
Posted 30 June 2009 - 04:22 AM
Yes. Autoguiding is a must for exposures that are more than a few seconds long.