pyro densitometry

[Jan_6568]

I am going to do film tests according to the BTZS procedure. I have step tablet negatives which I want to read using laboratory spectrophotometer instead of regular densitometer. One of the reasons is that I just do not have a densitometer while I have an access to the spectrophotometer. The spectrophotometer lets me to set desired wave length for mettering. It covers almost entire visible and UV spectrum. The question is what wave length to use to read pyro negatives intended to print on Azo or graded paper.
Maybe someone would have a suggestion.

Jan Brzeski

[sanking]

I am going to do film tests according to the BTZS procedure. I have step tablet negatives which I want to read using laboratory spectrophotometer instead of regular densitometer. One of the reasons is that I just do not have a densitometer while I have an access to the spectrophotometer. The spectrophotometer lets me to set desired wave length for mettering. It covers almost entire visible and UV spectrum. The question is what wave length to use to read pyro negatives intended to print on Azo or graded paper.
Maybe someone would have a suggestion.

Jan Brzeski

I would suggest in the blue at about 450 nm. And put a UV blocking filter over the light source since both graded papes and AZO have a lot of sensitivity to UV light.

Sandy

[Jan_6568]

Thank you, Sandy. Do you mean UV filter on the printing light source? I do only contact prints and use 120W flood light bulb hanging some 1 meter above the printing farme as a light source. It gives reasonable printing times with Azo, for graded bromide paper I use regular 40W bulb. I do not have any idea how to place a UV blocking filter on the bulb.

One more question: could you suggest apropriate wave length for POP paper?

Jan Brzeski

[sanking]

Thank you, Sandy. Do you mean UV filter on the printing light source? I do only contact prints and use 120W flood light bulb hanging some 1 meter above the printing farme as a light source. It gives reasonable printing times with Azo, for graded bromide paper I use regular 40W bulb. I do not have any idea how to place a UV blocking filter on the bulb.

One more question: could you suggest apropriate wave length for POP paper?

Jan Brzeski

If the 120W flood or 40W bulb is in a reflector you could tape the UV blocking filter to the bottom of the reflector.

POP is sensitive to UV light. I don't know the exact wave length of greatest sensitivity, but I think it would be somewhere between 380 nm to 420 nm.

Sandy

[Jan_6568]

Thank you, Sandy.

Jan Brzeski