Film testing - Plotter program help

[Jan_6568]

Some time ago I had FP4+/Pyrocat HD (dilutions 1+1+100 and 2+2+100) combination tested by View Camera Store according to BTZS procedure. The results were strange, especially film speed data: for 2+2+100 I got about ISO 60 and for 1+1+100 film speed was ISO 16 on avarage (ranging from ISO 6 to ISO 48). I asked here about those data and the answer was that something had to go wrong with the test. Also my own experience showed that in my hands FP4+ in Pyrocat HD gives about ISO 100-120. I measured the test negatives on my own then using laboratory spectrophotometer instead of densitometer. I do not have a densitometer but I do have an access to the spectrophotometer and in addition spectrophotometer allows setting desired wave length. I am printing on graded paper, Azo and POP so according to Sandy King's advices I measured the negatives using 450 and 400 nm light. My own measurements and data analysis showed ISO 120 for 1+1+100 dilution (I did not measure 2+2+100 negs yet) what suggests that my reading was correct and this was the source of problems. Now I am looking for someone who has Plotter program and would be so kind to plot the data for me to verify my analysis and to generate files for Palm program.

Jan

[Kirk Keyes]

Jan - one thing to consider is that a spectrophotometer will give somewhat higher absorbance/density readings that a densitometer.

It has to do with the geometery of the light source, the detector, and the amount of diffusion associated on each side of the film. Most densitometers are designed to read a diffuse light source next to the film and have a detector that reads most of the diffused light that passes through the film. The spectrophotometer has a specular light source due to the distance the light travels to get to the film, and it measures a specular reading due to the distance of the detector. THis ends up giving higher densities with the spectrophotometer.

This does not mean that your measurements are bad, they just may not match up with other people's measurements. And it may indicate that you are overdeveloping somewhat, when you are actually right where you would want to be if you had made measurements with a densitometer.

[Jim Noel]

I do not have access to a UV densitometer although I do have a color one so I can only read the blue channel which does not give me a true reading of effective film density with the stain.
I did not believe Sandy concerning film speed in Pyrocat HD until some practical experience proved it to me.

I had been using an EI of 80 for FP4+. The negatives were beautiful and printed in 5 or 6 minutes on VDB. Mistakenly I exposed a set of negatives at somewhere between 100 and 120, developed them in the same 2:2:100 Pyrocat HD dilution. The negatives looked thin enough to worry me until I printed them and saw the nicely detailed shadows and the glowint skin tones which printed in 70-90 seconds. I have not printed these in platinum/palladium yet, but likely will have to use my slower UV source to get controllable printing times.
I now use an EI of 100 for this film.

[neil poulsen]

I was given the following relationship between L (from Lab) and density by an engineer at Gretag-Macbeth. He indicated that it wouldn't be a bona-fide Status T measurement, and that it may not necessarily agree with another densitometer, but it might be Ok for some purposes.

If L > 8
Y = ((L + 16)/116)^3
Else
Y = (L * 27)/24389

Density = -log10(Y)

I've not tried using this myself, though. I'm also thinking that it may apply only to reflective measurements. (Unless Status T stands for transmissive. Not sure, though.)

[sanking]

Now I am looking for someone who has Plotter program and would be so kind to plot the data for me to verify my analysis and to generate files for Palm program.

Jan

Jan,

Have you considered down-loading the BTZS program from the article by Jorge in the last issue of MagnaChrom? I have not personally worked with the program since I own and use Winplotter but a cursory look at the program suggests that it may have enough features to meet your needs in generating data for the Palm program.

Sandy King

[Jan_6568]

Jan,

Have you considered down-loading the BTZS program from the article by Jorge in the last issue of MagnaChrom? I have not personally worked with the program since I own and use Winplotter but a cursory look at the program suggests that it may have enough features to meet your needs in generating data for the Palm program.

Sandy King

Sandy,
thank you - I was not aware of this program. I just downloaded it but it seems it does not produce Palm program files.

Jan