View Single Post
  #1  
Old 19-07-2006, 08:25 PM
Striker's Avatar
Striker (Tony)
Whats visual Astronomy

Striker is offline
 
Join Date: Dec 2004
Location: Brisbane
Posts: 5,062
A perfect example of severe Field curveture Coma and vignetting

Hi Guys,

Gary Beal was kind enough to lend me a .5x focal reducer to test on the LX200R....I may be able to get an improvememnt over this with more spacing between FR and camera but I thought I would show an example for the purpose of those who dont know what Coma and vignetting is.

Coma/field curveture is all the outer stars pointing towards the center..means the field is not flat.
Vignetting is the dark outer background that surrounds the bright center image also surrounded by a circle..notice the real distinct bright center compared to the very dark outer background....these are both severe and actualy look a 100% better then the original.

On the other hand I was stocked at the image as my exposure where only 2 minutes and only 10 exposures in which case thats half the time exposures I normaly do with half the quantity....cant wait to find a suitable FR between .8x and .6x.
Attached Thumbnails
Click for full-size image (TESTComa-crop.jpg)
129.7 KB83 views

Last edited by Striker; 21-07-2006 at 03:10 PM.
Reply With Quote