Quote Originally Posted by RalphLambrecht View Post

Thanks for your support. I prefer the 31-step version, because it gives more data points, and hence, smoother curves. However, some 35mm workers have trouble reading the thin bars with their densitometers and prefer the wider 21 steps. On the other hand, they could use their enlargers and their enlarging meter if it provides a density function.
I use the Darkroom Automation Enlarging Meter for this purpose. It works very well as a baseboard densitometer, reading in stops with repeatability of about 0.02 stops in my experience. That's 0.006 optical density units. Overkill for a film curve, and less expensive than a decent used densitometer. I use a spreadsheet and type in the stops and let the spreadsheet convert to optical density (simply multiply by 0.3), calculate and subtract fb+f from a 'clear' area of the film, and draw the film curve.