Because of the yellow/green stain of the PMK negative, you will need to use a color densitometer and the 'blue' filter. Color densitometers are expensive, even when you can find one used. The Mantis densitometer is a black and white unit that uses a blue L.E.D. and will read PMK negatives accurately. It is about $600 or so brand new.(posted 9121 days ago)