The first obvious question is to ask if you have the Dichroic head or the older Acetate filter head? If it is the Dichroic head, have you have checked things like light leak around the filter and ensure that the filter totally covers the light when set to 170?
How are you doing the test? When I checked some Omega D5500 magenta filters from the 1980s and 1990s against the #5 Ilford using a standard 21 step wedge and Ilford MG FB, it was difficult to detect any difference.
Last edited by ic-racer; 02-12-2014 at 02:02 PM. Click to view previous post history.