Archived posting to the Leica Users Group, 2000/03/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> The > definition tells us that a lens is apochromatically corrected if > three wavelengths are brought to the same focus. But in optical > design we discuss errors in fractions of microns. Now if three colors > have a focal difference of one tenth of a micron, do we then accept > this as being "the same focus". (?) > If three colors have a focal difference of one tenth of a micron would it not then be likely that 3 (slightly other) colors have *exactly* the same focus (within a tolerance of zero microns)? If one plots the focus location as a function of frequency (colour) and this curve oscillates such that 3 different colours have the same focus then would this not fit this definition of apochromatic?