ND Foil for Aurora Flat Field Panels
To obtain the correct brightness level from the Aurora flat field with certain telescopes it may be necessary to add a neutral density foil. This will reduce the light level from the panel to a point where the correct flat field can be obtained. Foils of different values can be combined.
Our recommendation is that telescopes with a focal ratio of approx F6 will require an ND1.2 foil. For telescopes with a focal ratio of F4 then we suggest adding an ND0.9 to the ND1.2.
If foils are ordered with an Aurora Flat Field, then we will fit the foil to the filter before delivery. If this is not required, please notify us.
