From: "Howard" <howard.fink@nyu.edu>

Date: November 11, 2009 2:02:11 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: a comparison of two stacks

http://f1.grp.yahoofs.com/v1/wBf7SmVbCpepXqBilr0gxMzGolAZSxUZszbYMAaT-4kX1NcMSY05iBqArv9_KM2EJnYr27hjro5I9f3On04vaotudfQ/Lunar/comparison.jpg

The images are cropped from the originals and enlarged 200%.  They use the same source movie, converted to avi for Registax at no compression, best frame rate and millions of colors.  The AstroIIDC image retained more of the original width.  The Registax stack had one big hole and some ragged edges.  The Registax has artifacts introduced; a bunch of parallel lines.  It's sharper but darker.  The astro is a bit softer but the color is better.  It also responds to the levels control in photoshop more smoothly.  Setting levels from the registax result never gave me the long shadow of a mountain just on the terminator without blowing out everything else, while the astro lets me control the contrast of the mountain shadow while retaining contrast of the rest.

  The image I submitted yesterday was only 3 seconds long, and every frame was 90%.  These exposures are a minute long and only 6 frames made it to 90% CI. These were both stacked at 80% CI.  

Howard Fink