# ISO speed determination constants - question for Stephen, Bill etc

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• 03-18-2013, 09:44 AM
AndreasT
Actually I want contrasty shadows and often slightly soft highlights. I do this is my processing since I do flash more than most I expect. Not to save a print but to give me softer warmer lights and colder harde shadows.
I have just always been looking for films which have straight line. As well as fitting it to my paper a bit. Somehow think that is right. Althought I think it is wrong.
What I have also thinking about. If we take a straight line from A-B the distance is short, however if we take a curved line from A-B the distance is longer. Translating this to photography the curved line would give us more grey tones. Making it warmer to the emotion.
Is this the magic of old films.
• 03-18-2013, 10:02 AM
Michael R 1974
I don't follow your A-B logic. That only applies to geometry. Assume a straight line between A and B. That means local contrast between any exposure value is equal between A and B. If you curve the line AB (whether concave or convex), you increase local contrast in some part of the curve relative to the straight line, and decrease it somewhere else in the curve relative to the straight line.
• 03-18-2013, 10:11 AM
Michael R 1974
Here's an interesting tidbit concerning film curve vs paper curve. In formulating his DI-13 developer for TMax 100, Phil Davis sought to create a D Log-H curve that was slightly flatter in the midtones (~Zones IV-VI) and steeper in both the shadows and highlights. The idea there was an attempt to counteract/offset some of the compression of highlights and shadows in the curve of the printing paper, rather than compounding the compression.
• 03-18-2013, 10:17 AM
AndreasT
If one disregards the local contrast say in a film curve, if it is concave or convex, or both. If we go from the toe to the highlights on a pronounced S-curve the grey tones should be expanded giving more grey tones. On a straight line the tones are contracted.
I am not saying one is better than another. It is of course impoertant what paper we use and how we enlarge the picture if hard or soft.
Just the distribution of the tones on the film curve. I would say a "modern" straight line gives us superior local contrast while a "old" film gives us more grey, softer shaows and lights but an increased contrast in the mid tones.
This comes back a bit to the four quadrant reproduction curve graphs.
• 03-18-2013, 10:33 AM
Michael R 1974
I don't see how you can disregard local contrast in the film curve when looking at the "number" of grey tones. The net different in D between two points is the total contrast. The shape of the curve in between those two points determines local contrast, but total contrast has not changed.
• 03-18-2013, 10:54 AM
AndreasT
I am only disregarding local contrast to think about tones. If we minus develope we get more grey tones, lengthening the curve. That leads me to think that a curvy curve (funny writting that) gives more grey tones.
• 03-18-2013, 08:10 PM
Stephen Benskin
Quote:

Originally Posted by AndreasT
Actually I want contrasty shadows and often slightly soft highlights. I do this is my processing since I do flash more than most I expect. Not to save a print but to give me softer warmer lights and colder harde shadows.
I have just always been looking for films which have straight line. As well as fitting it to my paper a bit. Somehow think that is right. Althought I think it is wrong.
What I have also thinking about. If we take a straight line from A-B the distance is short, however if we take a curved line from A-B the distance is longer. Translating this to photography the curved line would give us more grey tones. Making it warmer to the emotion.
Is this the magic of old films.

Jones writes, It must be realized that the negative itself is only means to an end and it makes little difference what its characteristics are, provided a print of satisfactory quality can be made thereform...As a matter of fact, it seems logical to take the position that the characteristics of the negative may be anything so long as a satisfactory positive can be made...having the proper characteristics."

The negative density range is slightly larger in this example than the paper's LER. Depending on the scene, this may not matter, or can be control through printing techniques.

Attachment 65952 Attachment 65953

A technique I've used to bring out the local contrast of the midtones and lower midtones is to develop the film for normal, use an unsharp mask to control the highlights, and print on a higher grade of paper.
• 03-18-2013, 09:26 PM
AndreasT
Yes I myself use unsharp masks for my large formets. I was amazed the first time doing it.
• 08-16-2015, 12:32 PM
Bill Burk
Quote:

Originally Posted by AndreasT
I agree Stephen

This sometimes make me wonder why all the effort. When the scene is contrasty we compensate developement and need a harder grade to get the contrast back into the picture otherwise the brilliance suffers. It fits on the paper sure.
What if we always expose and develop normal.

Oh shoot. I guess this means I may have the wrong mental picture of Delta-X.

It goes back to the reason you developed to a thin negative. If it was a normal scene, underdeveloped... then Delta-X justifies holding your Exposure Index constant for the "contrasty paper" you have to print on. But a long scale scene, underdeveloped, would haver been intended for a "normal paper".
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