Got Stoffer 21 Step Tablet, Densitometer? Pls Help

[Andre Noble]

I am wondering if anyone who owns a Stouffer 21 step tablet (0.15 increments type) and also a densitometer machine at home who might be willing to do a very quick and dirty reading of each the 21 steps of the stouffer tablet itself and post them here? (when you get the opportunity).

I am making contrast masks for Ilfochrome using an "uncalibrated" 21 step Stouffer that goes in 0.15 increments. I don't know what the darkest density reading is. I assume the lightest starts at 0.00 and finishes at 3.00. Is this true/accurate enough for now?

The reason I need the info is to due some rough plotting, calculating, and judging of my mask densities and contrasts, and I have very minimal prior experience. This info would be most helpful (until that fine day when I can afford a densitometer of my own).

Thanks for any help.

Andre

[Alan Sugiyama]

Andre, Here are some values from two different Stouffer calibrated 21-step tablets. Each step will have two values. The first by Stouffer on the envelope and the second value I measured on a Brumac T/R densitometer I was using at the time (10-'88).



Tablet A Tablet B

Step Number Stouffer Brumac Stouffer Brumac

1. .06 .05 .06 .05

2. .21 .21 .20 .20

3. .35 .36 .35 .36

4. .52 .51 .50 .50

5. .67 .66 .64 .64

6. .81 .80 .80 .79

7. .96 .95 .94 .94

8. 1.12 1.11 1.09 1.08

9. 1.27 1.25 1.25 1.24

10. 1.43 1.41 1.41 1.40

11. 1.59 1.56 1.55 1.54

12. 1.74 1.71 1.70 1.68

13. 1.88 1.85 1.85 1.82

14. 2.03 2.00 2.00 1.96

15. 2.17 2.13 2.15 2.12

16. 2.33 2.28 2.32 2.26

17. 2.46 2.42 2.47 2.40

18. 2.62 2.57 2.62 2.55

19. 2.80 2.75 2.77 2.69

20. 2.94 2.88 2.92 2.84

21. 3.08 3.01 3.10 3.01

I seem to be losing the formatting of my reply.... If you see four values across the page after the

step #, the first pair belong to Tablet A, the second pair to Tablet B. The first value of each

pair is the Stouffer value written on the envelope, the second value is my reading taken with the long-departed Brumac.

I plan to recheck these step tablets on my newly acquired X-Rite 810 when time

allows........but don't hold your breath! Hope this helps!

Alan

[Chris Gittins]

I have an uncalibrated Stouffer 21 step and an X-Rite 320. Lord knows the last time the X-Rite was calibrated, but when I first fired it up and checked the tablet, Step 1 read ~0.05. Increments are nominally 0.15 and density is very linear with step number all the way up to Step 21. Alan's data bears that out.

It makes sense that Step 1 is ~0.05. That corresponds to transmission of 10^-0.05 = 0.90 = 90%. Reflection losses should be about 4% per surface, so 90% transmission sounds about right if you figure there's also a little absorption within the film itself.

Chris

[Andre Noble]

Thanks Alan,

I appreciate your taking the time to retrieve and post that data. Thank you very much, and Chris, thanks for corroborating with that additional technical info.

Andre