New Kodak support decreases UV transmission

sanking

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It was pretty shocking to me as well when I found that the transmission loss was on the order of three full stops for the new TMAX-100 film. As best I can remember Clay and I were among the first to realize the change, and our findings were later supported by specrophotometer tests done by a scientists the RIT who came to his finding independently of our work.

No question about it, even with light sources that produce a lot of radiation in the near visible and visible range the loss is about three full stops.

Sandy
 

sanking

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reggie said:
Sandy:

Will the ULF-28 put out enough UV light to shorten the exposure times?

-R
Click to expand...

No, the ULF-28 puts out its radiationi in the same area of the UV blocking so in spite of the fact that it is a a faster printer than most commonly used light sources three stops light loss is too mucn of a handicap to overcome.

Sandy
 

TheFlyingCamera

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For a light source that might work for you, look into the Kino-Flo fluorescent lightbanks. They're not cheap, but you can get them with EIGHT 75w BLB tubes. In the Intro to Platinum class I took at CFAAHP with Carl Weese, we were getting 1 - 1.5 minute exposure times with the lamps at full power. Cutting the power to all tubes by half brought the exposure times down to 2.5 - 3 minutes. The 8 tube unit would be big enough to print 20x24.
 
OP
OP

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A wedge spectrogram of Azo paper indicates to me that it has about 1/2 of its sensitivity in the blue region. Tests of cyanotype and other alternative process materials show little or no sensitivity in the blue region.

We could run some tests at my workshop with the AgCl emulsion that I make to see what proportion of the sensitivity is in the blue and what is in the UV, but that differs from real Azo, in that Azo has other ingredients to enhance speed to visible light.

Bottom line, Azo users will see this to a lesser extent, I think, than cynaotype printers. IDK about VDB or Pt/Pd printing. I'll have to test it I suppose. I really don't want to though.

PE
 

c6h6o3

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Photo Engineer said:
Bottom line, Azo users will see this to a lesser extent, I think, than cynaotype printers.
Click to expand...

The problem for me in printing Tmax 100 negatives on Azo is not the loss of speed but the complete lack of contrast. Flat, flat, flat no matter what I do.
 
OP
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c6h6o3 said:
The problem for me in printing Tmax 100 negatives on Azo is not the loss of speed but the complete lack of contrast. Flat, flat, flat no matter what I do.
Click to expand...

Have you tried D8 or D19 developers?

PE
 

David A. Goldfarb

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I can get enough contrast with old TMX for albumen printing in D-76 (1+1) 16min. at 75 deg. F. Just processed my last four sheets, so I don't need that info anymore. Here's one I've posted before--

http://www.echonyc.com/~goldfarb/temp/grant2005albumen.jpg

I think the "flat" look of TMX is a spectral sensitivity issue. It can look a lot like B&W video or digital B&W straight from a digicam under certain lighting conditions.
 
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