Originally posted by Stone G. I am familiar with this article and always found the first example photograph to be amusing. I have seen severe PF and that is not it
When I think PF, I generally think of a wedding shot where the bride's arm is purple from wrist to elbow! Or perhaps the more classic bare branches against sky where the branches are "webbed" with violet glow. Beyond that, the author of the article is pretty clear that he is describing CA (both lateral and axial) and offers the hypothesis that the digital sensor amplifies the problem.
An interesting matter for discussion is the fact that some lenses that are supposed to be notorious for PF have very low measured CA (the FA 35/2 and FA 77/1.8 being prime examples). Klaus at Photozone is always careful to make a distinction in his lens reviews. It is also good to note that CA usually increases from large to smaller aperture while PF decreases.
For what it is worth, most films (color and b&w) have significant blue-end sensitivity extending into the UV. This traditionally has been problematic in terms of blue shift due to reciprocity failure on long exposures and unwanted haze for landscape work (hence the common use of a UV filter for color work). If the lenses were optimized for film sensitivity, one would expect that the blue end of the spectrum would be more accurately focused, not the other way around.
Steve