Apochromatic doublet

Apochomatic Doublet

Is a lens with 2 types of glass processed against each other, where 1 type of glass has a low color error. Actually, an apochromat is a lens with 3 types of glass facing each other.

But due to current coating techniques, doublet lenses are also called apochromate. This is because they have the same optical values.

Manufacturers can thus deliver a good optical telescope cheaper to the customer.