Front Page

 

The Old Set of AstroDon Gen I Filters Suspected to Lead to Degraded Images

 

Further Test by Rotating the Filters 180deg

 

 

The Resulted Null Flat (On Left side) Remains as Smooth (albeit a little cleaner after further cleaning the CCD Chamber Window)

 

Resulted Luminance Flats (on Left Side) Vs Original

 

 

Resulted Red Flats (on Left Side) Vs Original

 

Resulted Green Flats (on Left Side) Vs Original

 

Resulted Blue Flats (on Left Side) Vs Original

 

Observation :

The shifts in uneven illumination patterns along with the rotated filters are clearly discernible. These shifts would have been even more obvious if not masked by the superimposed general light gradient perhaps due to an imperfect light shield, twilight gradient, etc.

 

Other Filters for Comparison

Baader Ha Flat

 

Baader SII Flat

 

Baader OIII Flat

 

Observation:

1. There are no central hot spots in the Narrowbands flats.

2. The illumination patterns are smoother and there are no uneven illumination patterns so obvious in the LRGB filters.

 

A Discovery

A possible Crack (in the substrate?) of the Luminance Filter (position 1): the white dot (with its reflection) on one side