It's not really magnification, it's the objective focal ratio of the scope.
On a refractor, you have an objective diameter which are commonly 24, 40, 42, 44, 50 or 56mm and then you have the focal length which for simplicity you can take as the length of the scope.
A lot of scopes are around 300mm long (1 foot) so the focal ratio of a 50mm objective scope is about 6 (300/50).
Now if you look at a simple achromatic doublet refractor telescope, if your focal ratio is around 15 or higher, you won't see CA. If you start using ED glass, you can get around 9-10 without seeing too much CA, if you get faster than that, you need to step up to a $$$ apochromatic triplet objective to avoid CA.
Magnification is determined by dividing the objective focal length by the eyepiece focal length so if you can make your eyepiece focal length short enough, you can get as much magnification as you want regardless of CA but practically speaking, packing high magnification in to a scope is tricky and usually results in optical compromise unless you spend a lot.
On a refractor, you have an objective diameter which are commonly 24, 40, 42, 44, 50 or 56mm and then you have the focal length which for simplicity you can take as the length of the scope.
A lot of scopes are around 300mm long (1 foot) so the focal ratio of a 50mm objective scope is about 6 (300/50).
Now if you look at a simple achromatic doublet refractor telescope, if your focal ratio is around 15 or higher, you won't see CA. If you start using ED glass, you can get around 9-10 without seeing too much CA, if you get faster than that, you need to step up to a $$$ apochromatic triplet objective to avoid CA.
Magnification is determined by dividing the objective focal length by the eyepiece focal length so if you can make your eyepiece focal length short enough, you can get as much magnification as you want regardless of CA but practically speaking, packing high magnification in to a scope is tricky and usually results in optical compromise unless you spend a lot.
