|
That must be referring to chromatic aberrations. Basically when light travels through glass different wave lenghts (colors) have different paths so they deviate and will end up focusing at different points.
So you get purple halos, colour fringing, etc... Some filters will help with that. Like the Baader Fringe Killer for lenses.
SCTs are sometime catadioptrics systems. They're a mix of glass (correctors) and reflective components (mirrors) so you can get some colour halos on your stars.
Every scope that uses a correcting lens such as a coma corrector or field flatener will have a refractive element.
High end refractors have many lenses stuck together to get rid of color fringing. You have triplets, quadruplets, etc... with different type of glass in each layer. Some have air spacing, others even oil spacing.
I think it's safe to say that most LRGB filters and narrowband filters would work on all telescope types.
Specialty filters Fringe Killer, etc... are for refractors.
|