PMK and zone 8 density

[Shen45]

Does anyone have the density reading through the blue channel of a zone 8. A friend uses PMK and while I have a densitometer it is a B&W job. We can possibly borrow an Xrite next week to check if we have a figure to work from.

He is shooting 5x4.

Can you provide a Z8 measurement zeroed out on the light of the densitometer and one zeroed out on film base.

TIA

Steve

[steve simmons]

I use a reading of about 1.35 above fb+f. Gordon Hutchings prefers a higher reading, something between 1.5 and 1.6. This is to make zone 8 just barely perceptably darker than pure paper white. He sues a #2 filter on vc paper and I do not use a filter which is about the same as a #2 filter on vc paper.

steve simmons

[Shen45]

Interesting figures -- thank you. It gives me a starting point.

Steve

[sanking]

I use a reading of about 1.35 above fb+f. Gordon Hutchings prefers a higher reading, something between 1.5 and 1.6. This is to make zone 8 just barely perceptably darker than pure paper white. He sues a #2 filter on vc paper and I do not use a filter which is about the same as a #2 filter on vc paper.

steve simmons

Thank you for providing these densitometer readings. Assuming that the B+F values of these negatives are normal the Zone 8 readings indicate that you and Gordon Hutchings are developing your negatives to a fairly high CI, which should allow you to print scenes of normal contrast with a #2 VC filter, or no filter.

Basically there are two options with pyro developers for silver papers.

1. Develop the negative to a fairly low CI so that it prints with normal contrast on graded silver papers, and then use high magenta filtration to get sufficient contrast for VC papers. This has the disadvantage in that if one must resort to a VC filter of #3.5 or higher (or dial in an equivalent amount of magenta filtration on a color head), highlight compensation will be lost. This is because the magenta filtration will reduce or eliminate light to the low contrast green sensitive areas of the emulsion, which in combination with the filtration provided by the stain color is responsible for compensation. An advantage of this approach is that it makes BTZS more precise with VC papers since the color of the stain is neutralized.

2.Develop the negative to a fairly high CI so that it prints with normal contrast on a VC filter with a #2 or #2.5 filter, or no filter, and then use low contrast VC filters to reduce contrast with graded silver papers. This makes BTZS less precise, but retains highlight compensation.

In spite of the fact that I am a BTZS user I prefer and recommend the second approach since it retains highlight compensation, which is for many people one of the most important characteristics of pyro developers when printing on VC papers.

Sandy King

[Shen45]

Thanks for the replies Steve and Sandy,

In another post I detailed my results with PMK and BTZS, and had also arrived at your second option Sandy of increasing the paper ES in my exported ExpoDev file to give me the type of negative that prints well on a VC paper at about a grade 2 equivalent.

Coincidentally [for those thinking in zone terms] a blue channel reading of 1.55 reads close to a B&W densitometer reading of 1.2. These figures will vary a small amout due to individual processing methods but may be a way for someone without a colour densitometer to get an approximate idea of the highlight reading they are achieving if using VC paper.

Steve

[sanking]

Thanks for the replies Steve and Sandy,

In another post I detailed my results with PMK and BTZS, and had also arrived at your second option Sandy of increasing the paper ES in my exported ExpoDev file to give me the type of negative that prints well on a VC paper at about a grade 2 equivalent.

Coincidentally [for those thinking in zone terms] a blue channel reading of 1.55 reads close to a B&W densitometer reading of 1.2. These figures will vary a small amout due to individual processing methods but may be a way for someone without a colour densitometer to get an approximate idea of the highlight reading they are achieving if using VC paper.

Steve

I read with interest your post on PMK and BTZS. It is good to see people working with pyro staining developers and BTZS. There is some small loss of precision with BTZS compared to non-stained negatives, but on the whole it is less of a problem than some people claim.

BTW, processing methods are not the only thing that can impact the diffference in readings between Visual (Green) readings and Blue readings. There is also a difference between pyrogallol based staining developers and pyrocatechin based ones. For example, in one of my tests a PMK negatives that reads 1.32 in Visual (Green) reads 1.62 in Blue and 2.18 in UV, while a Pyrocat-HD negative that reads 1.32 in Visual (Green) reads 1.49 in Blue and 2.25 in UV. The difference between Visual and Blue readings of PMK and Pyrocat-HD appears to be typical of pyrocatechin based and
pyrogallol based developers, though I will stop short of claiming that it is true of all formulas.

Sandy King