Re: [APML]new technique?

[Chris1011@aol.com]

In a message dated 11/13/2001 8:36:21 AM Pacific Standard Time, tonyhallas@foothill.net writes:


>  This "technique" escaped me in the past because going"portable" you would never shoot 6 negatives of the same thing....but having an observatory changes all that.


Hi Tony,

This is standard procedure for CCD images. For my work, I tend to shoot only one subject per night, sometimes I shoot it again for several nights in a row. This is the only way I found to reduce the noise when shooting at long focal lengths where the density of the nebular detail is low compared to the background. It would be interesting to do a comparison of CCD vs. film with various number of stacking. I find that I need to stack at least 5 images with my ST10E camera. Each image takes about 12 minutes counting the download time (I could go longer for each image and reduce the noise level, but then the stars will begin to bloom). So for a full color RGB, it takes a minimum of 3 hours to get one really nice color image, plus perhaps another hour to take a luminance image. In that amount of time you could take quite a few film images for stacking.

Roland Christen