View Single Post
  #4  
Old 18-10-2009, 09:04 PM
jase (Jason)
Registered User

jase is offline
 
Join Date: Sep 2006
Location: Melbourne, Victoria
Posts: 3,916
Yes. Takes a little getting use to Maxim's screen stretch. Quite powerful and useful.

In the minimum field enter 0 (zero) and hit enter. This will place the red triangle (black point) as far left as possible. Then hit the + magnifying glass to zoom into the histogram more. As you zoom, you'll be able to raise the red triangle and lower the green triangle (white point) to display the data you want to view.

I'm not sure what you've taken an image of, but the signal is weak. Imaging is a numbers game. Despite what many believe, FITS files aren't conventional image binary files, but series of numerical values. This provides incredible flexibility allowing the imager to multiple/add/subtract values to all pixels to fill the bit space (16bit or similar).

If I was to judge your data, I'd say you need more exposure time. 3 minutes isn't going to cut it. The info window shows that the minimum pixel is 1063 counts with the average 1433 counts. This will change where ever your cursor points, but for an average to be so low is probably a good indication more exposure time is needed. The maximum of 65k will be hot pixels or saturated stars. The info window are real values i.e. you can screen stretch the data as soft or as hard as you please, but the pixel values remain the same. Screen stretch does not manipulate the image data itself, just how its presented on the screen buffer.
Reply With Quote