Although very fast and with a very sharp wide field of about 6x9 degrees, my 5.5 inch celestron schmidt camera vignettes quite severely due to its corrector plate and mirror being close to the same size. Up until recently, t his has been a tedious problem to correct manually in Adobe Photoshop. Thanks to the many suggestions to try Picture Window Pro from the APML group, the quality of the images has been dramatically improved with this superb software, and it also has the best curves function in the industry for processing all astronomical images. Below is the comparison of before and after apply the "Light Fall off" filters with this program and how well the damaging vignette was greatly reduced. The left image is the original, a 10 minute exposure on Kodak PJ400 taken last month. On the right is after the correction in PWpro.

Instrument:  5.5" f/1.65 Celestron Schmidt Camera
Platform:  Astrophysics 1200 QMD
Film:  PJ400
CCD Autoguider: ST-4
Exposure:  10mins
Filters:  None
Location:  Payson, Arizona
Elevation:  5150 ft.
Sky:  Seeing 8/10, Transparency 8/10
Outside Temperature:  0 C
Processing:  Photoshop, PW Pro.

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