Steve, The most likely reason for trailing in the image, if the autoguider is holding the star in position, is differential flexure. Is it possible that the guide scope mounting is not solid enough? I have run into this problem many times. Check to make sure your guide scope attachment is absolutely solid. That may fix your problem. Cheers, Tyler -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Stephen Peterson Sent: Friday, November 05, 2010 11:22 AM To: utah-astronomy@mailman.xmission.com Subject: [Utah-astronomy] Photo question Anyone: I told you all it wouldn't be long before I had more questions! When I select to reduce the size of a JPEG file (to be taken by the camera) is this equivalent to "binning". If so, does the larger effective "pixel (s)" reduce noise as larger pixels are wont to do? Still working the bugs out of the autoguider, it seems that I am getting worse trailing with the auto guider (under higher magnification) than without guiding for 1 to 2 minute exposures. WX good here in S Utah so will continue to debug. Thanks for any help! Steve _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com