Archived posting to the Leica Users Group, 2000/08/21
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]"Henning J. Wulff" wrote: > I'm sorry, Horst, but this isn't true. Apochromatic correction of a lens > has nothing to do with the overall spectral response. Neither does it have > anything to do with coatings, or flare level, or distortion or any one of a > number of other aberrations. All it means is that three wavelengths in the > visible region of the spectrum will focus on the same plane. It does not > even mean that the rest of the wavelengths are focussed within a small > distance of the same plane. > > Of course, most manufacturers of general use lenses try to do a good job of > other aspects of aberration correction and quality design when going to the > trouble of making an 'Apo' lens, but that is a different matter. > > * Henning J. Wulff > Henning, thanks for your kind explanation. It makes sense to me. When I said spectrum, I actually meant the 3 primary colours. I hadn't thought of all the other colours in between. Thanks again. Regards, Horst Schmidt