They are supposed to look like that. I have never seen a spectrum analysis of the 4-5 filters, but an interrogation with a standard wide-band baseboard color meter does not give the full story. I suspect they (#4-5) are special narrow bandpass filters.
This link is to one of the best collections of information about the various color schemes Ilford has used for MG materials. http://www.photomemorabilia.co.uk/Il...ultigrade.html
Last edited by ic-racer; 01-01-2012 at 11:30 PM. Click to view previous post history.