View Single Post
  #11  
Old 01-11-2007, 09:10 PM
Terry B's Avatar
Terry B
Country living & viewing

Terry B is offline
 
Join Date: Mar 2006
Location: Armidale
Posts: 2,760
I superimposed the little image on the big one using the gimp and got a rough measurement of 150 pixels wide compared to the big image of 720 pixels. This gives you a focal reduction of ~0.21x
I don't know the focal length of your scope but just multiply it by ~0.2 to give a pretty close estimate.
To get a much more accurate estimate you need to plate solve a star field through the focal reducer. I have an old version of AIP for windows that I would use to do this. I'm sure there are other programs that can do the same.
Attached Thumbnails
Click for full-size image (merge.jpg)
25.6 KB13 views
Reply With Quote