Yes, if you just want to use the densitometer for process control, you probably don't need any exact filter. Just read the negative the same every time. Say, for example, you have a Pyro negative of your typical subject that was processed with a development time determined by trial and error, such that it prints well around grade 1.5 to 3. Then process a control strip with those same conditions and see what the gamma is. You can check it with all 3 colors and document this as your baseline.
Originally Posted by Bill Burk
In the future if you prints are not coming out right, you can re-check a control strip and see if the color (stain) or gamma has changed from your original control.