</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (David A. Goldfarb @ Feb 5 2003, 02:19 PM)</td></tr><tr><td id='QUOTE'>
My theory on this is that VC papers have a wider spectral response than graded papers (otherwise the filtration wouldn't work), so they will show up chromatic aberration in the lens more than graded papers, depending on the filtration, the lens, and the light source. If you use an apochromatic lens or a narrower band light source or a strong monochromatic filter, you shouldn't have a serious problem with chromatic aberration, so you might not notice a difference under those circumstances.</td></tr></table><span class='postcolor'>
Chromatic abberation as an error in a lens system affects black and white media nearly equally as severly as color media.
The Spectral sensitivity of "Graded" (non-variable contrast) paper is not restricted to a narrow spectral band ... and few enlarger light sources (actually, none that I know of ) are to any great degree monochromatic. Chromatic abberation is caused by a lens design that focuses different wavelengths of light to converge to differing points ... and the worst case of that I ever encountered was in a Kodak Contour Projector - where the edge of a silhoette projected to the exteremes of its 30" screen were red on one side and blue on the other. Another Comparator manufacturer (Jones and Lamson) offered a monochromatic light source - a mercury vapor lamp - to avoid just that effect.
Enlarging lenses -- every one that I've ever been in contact with - seem to have *very* little chromatic abberation - as a design criteria.