Local Gamma and the workings of VC paper

[Kirk Keyes]

Warm-tone simply doesn't go down to 00 with acceptable performance.

That's really the important thing to note here, I think.

 

[Rafal Lukawiecki]

Nicholas, I have never seen any of my step wedge prints do that to that extreme. What paper and printing conditions were you using?

In fact I have plotted the curves of several papers using my Ilford 500 head and I get nice smooth curves on most papers. Most of my tests have been on Forte Polywarmtone, Ilford MGIV, and Ilford WT.

Sorry to dig-up an oldish thread, but I am fascinated with this issue of potential flat-spot in the middle tones of MG papers used at the 00 grade. In particular, I am curious how it affects split grade printing, which I have used a lot in the last few years.

I was wondering if the reason L Gebhardt did not notice the issue that Nicholas has described in his PDF could be related to the use of MG composite filters as opposed to the application of the "binary" dichroic Ilford 500 head.

On another note, it makes me wonder if split grade ability to produce well delineated middle tones is dependent on the choice of the light source filtration.

Many thanks,
Rafal

 

[Nicholas Lindan]

flat-spot in the middle tones of MG papers 00 grade. In particular, I am curious how it affects split grade printing

The shape of the 00 HD curve has the same effect in split grade printing as it has in graded filter or VC/Color head printing.

On another note, it makes me wonder if split grade ability to produce well delineated middle tones is dependent on the choice of the light source filtration.

Split-grade printing has no greater or lesser claim to delineated tones than any other method of VC printing. The paper response is identical in all methods as all they do is to control the relative exposure of the blue sensitive and green sensitive emulsions. The light source has no bearing as long as it can be filtered adequately, a problem with some cold-light and color heads.

S-G does have a slight advantage in that it is possible to get finer control of paper grade. In practice, as near as I can observe, most S-G printers use techniques that result in fewer paper grades.

S-G's emphasis on determining contrast with 2 test strips, one for highlights and one for shadows, gives no direct control over midtones. Getting midtone control with S-G is a bit of a crap-shoot as the two exposures interact in the midtones. Some people seem to have developed a feel for using midtones in S-G printing.

Tone reproduction, as a rule, is worse with VC papers than with graded papers.

The application note on split grade printing on the Darkroom Automation web site may provide more insight.

http://www.darkroomautomation.com/support/appnotesgmeasured.pdf

 

[Ian Grant]

I wonder if the 00 curve is being affected because you're using a cold tone, relatively contrasty, developer with a warm tone paper to achieve low contrasts. That combination doesn't make any sense.

Ian

 

[ic-racer]

I wonder if the 00 curve is being affected because you're using a cold tone, relatively contrasty, developer with a warm tone paper to achieve low contrasts. That combination doesn't make any sense.

Ian

You are referring to Nicholas' post : "Ilford MGIV WT FB, D-72 1:2 3 minutes" ?