The new flatscreen of Gerd Neumann contains a illumination flatfieldfoil (high voltage/low current) embedded in a plastic frame sandwich.
How to fix this flatscreen box in front of the cassegrain? A special base plate, with a size just smaller of the diameter of the primary focuser, was build and combined with an old 2 zoll adpater. This locking adapter was glued on the center of the transparent screen in order to allow the fixation of the flatbox into the primary focuser in front of the cassegrain.
The illuminated assemply just fits, with a foildiameter of (42x42)cm, in front of the cassegrain and the 42cm mirror. The flat frames can be exposed in every position of the cassegrain, even in the closed observatory in preparation of the night session.
The full field is equally illuminated.
The flat of the Cassegrain/STX16803/65mm filter/secondary corrector...