I am one to recommend some testing, but the minimum necessary to get what you want. I just test for Z 1 to get film speed and Z VIII to get contrast, and don't worry about the curve in between. Furthermore, I don't believe it is useful to test your film with a densitometer if you don't also test your paper. This is all very expensive and, unless you plan to be doing this regularly, is not worth the effort.(posted 8728 days ago)Good information can be found on circada.com bout the theory of testing, the process and building and using a diffuser, which is quite useful. I don't, however, believe that their sensitometric approach using a densitometer is worth the time or effort. Very different is a Shutterbug article which you can find on Tom Halfhill's homepage http://www.hooked.net/~halfhill/speed1.html and a part 2 on http://www.hooked.net/~halfhill/speed1.html. It deals with the very basics, is very simple and that is what is good about it. I have used these two sources, plus a dozen other books, to devise a simplified approach to testing.
Since I shoot 6x7, I have 10 shots on a 120 roll. I thus shoot the first frame of a piece of paper on which everything is written (this is not really necessary, but just a convenience), the second one by putting the lens cap on and closing the lens to the lowest aperture with fastest shutter speed (thus achieving 0 density above fb+f). Then I shoot the next four frames to get Z1 (four stops below an average reading) and bracket around what I guess is the approximate speed of the film. Thus for an ISO 400 I might guess that the real speed will come out 250 or 320 and shoot the frames at 4 stops below 200, 250, 320 and 400. This is followed by shooting the next four frames to get Z 8, and therefore 3 stops above the approximate speed I estimated above. All of this is processed at a standard time. The maximum black negative, the second one on the roll, is put in the enlarger carrier. I focus and make a series of test prints to get the first exposure that is completely black when dry. Then I choose from the Z 1 negatives to find the first one that gives the first hint lighter than complete black on the paper when dry. If this turns out to be the negative shot at 4 stops below ISO 320, I then take the negative shot at 3 stops above ISO 320 to get the Z 8 reading, and thus the contrast. If that turns the paper white I reshoot and develop for a lesser time. If it turns out a little too much darker than paper white (this is very subjective and probably a slight flaw in the system, although you should be able to make an educated guess), I increase the time. A modified procedure is used to achieve N- and N+ contrast. I am sure that my explanations appear very complicated to anyone who does not already know what I am talking about, but the Shutterbug article is much much clearer. The advantage of this technique is that it calibrates your negs to the paper that you are using. To calibrate various papers to each other, see The Variable Contrast Printing Manual by Anchell for VC papers (the calibration technique also works for non-VC papers). Good luck.