An achromatic doublet is typically made of a positive crown glass lens whose power is positive but which decreases with increasing wavelength (i.e. toward the red), cemented to a weaker flint glass lens whose power is negative and also decreases (in magni

So, if we can to correct the lens shown in Fig. 1,with an equivalent achromatic doublet we will set feq to 50 mm and choose two materials for our lenses. For the flint glass I’m choosing N-SF8 with an Abbe number of 31.31 and for crown glass I’m choos

With doublet achromat, the strongly curved two inner surfaces have by far the largest aberration contribution. Since their radii are typically similarly strong, and of opposite sign, so are their aberration contributions. Canceling of coma is done mainly