From: Alan Friedman <alan@greatarrow.com>

Date: April 22, 2008 10:28:21 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Manual Stacking question

I find it helpful to examine the frames and select a best frame - if only to get a sense of the quality of my data (and how much time to spend working on it). I do try to select the best reference frame, but I don't think it is imperative to choose the best - a good one will work fine. If you are shooting at a long EFL and working with a high noise level in your frames (as I often do) be sure to set the pixel matching for stacking to low or medium low and use the Gaussian blur option for frame analysis and alignment. If you use a higher level for pixel matching, the program will reject many of the selected frames for stacking.

Alan

On Apr 22, 2008, at 11:10 AM, doodlebun wrote:

With Astro IIDC set for manual stacking the program first does an
analysis and then presents a subset of frames that meet the Confidence
Interval set by the user.

Then each frame of the subset can be examined for retaining or not. How
important is it at this point to select the best frame you can find and
then check the box for the best frame? If unchecked does this mean that
that the software simply picks the first image for alignment?

I've had the experience of going through the tedium of manual selection
of frames only to have the program fail to align the images when I'm
done. When I first started imaging I thought the largest selection box
should be used for image comparison as the Mac I use is quite fast. But
I seemed to get into trouble. After OK'ing the confidence interval
screen, the program would give me a stacked image composed of only the
fifirst image. This seemed to be less likely to happen when I used a
96 X 96 grid.

When imaging Saturn I can have the planet oriented so the rings are
horizontal along the long (640 pixel) axis or any other way I want. Is
there a preferred way that allows the software to do the most accurate
stacking?