Hi Steve, Compression to jpg is not the same as binning. What camera are you shooting with? dslr's are different than monochrome cameras because they are "one shot". Each pixel is not devoted to every wavelength of light like on a monochrome camera. In a dslr, each pixel has a different color filter in front of it, this the Bayer Array: http://www.cambridgeincolour.com/tutorials/camera-sensors.htm Raw images have a lot more data in them, and are mapped to a deeper bit depth than a jpg image, which is only 8 bits, vs 12, 14, or 16. Shooting jpg is actually chopping gray levels out of each color channel, reducing the quality of the image. http://www.astropix.com/HTML/I_ASTROP/HOW.HTM That is a good link on how that works. I am not exactly sure what binning the pixels on a DSLR would do, but I think it wouldn't have any advantages. As far as the autoguider goes, I'm not sure what advice I could have there other than a better polar alignment? I use PHD and a webcam, there are a lot of settings you can tweak with PHD, never used a standalone guider. Cheers David On 11/5/2010 11:22 AM, Stephen Peterson wrote:

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

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