From: Ralph Megna <ralph@macastronomy.com>

Date: April 9, 2008 3:13:55 PM MDT

To: <Astro_IIDC@yahoogroups.com>

Subject: Re:Mathematics of Stacking

In my experience, even with relatively low-noise cameras, it takes 150-200 frames to create a smooth image. In ordinary webcams, it takes at least 3x that number.

Increasing the number of frames, if it involves lowering the quality threshold, is not a good idea, even if only for the color channels.  “Smoothness” is mostly a factor of the luminance channel, anyway.

I am not sure if there is a mathematical formula that determines the point of diminishing returns, but my guess is that improvement of the stacked image falls off after 800 to 1000 frames — again, that would be especially true if you are using a scientific/industrial camera, and not a webcam.

Ralph Megna

Riverside, CA