Film test results

[Stephen Benskin]

Those readings were made using a sensitometer. Oh, and those readings are of the negatives. Of the areas representing zones V, III, and VIII. I remember when I did this testing in a class I took, we read the negatives for the densities, however, now, in the handouts from that class, I can't find what the densities are supposed to be. All I can find are what the densities are supposed to be on a print/enlargement. I also checked The Negative and AA only gives the densities for the print--not the negatives.

You read the negatives with a densitometer, not a sensitometer. Two very different things. You can find a table of aim densities on page 220 of The Negative. You can also use the curves in Appendix 2 to extrapolate the aim densities.

Why don't you read the edge of the film for the fb+f?

[Drew Wiley]

Gosh. There are all kinds of paper out there too. Just put the damn thing in the enlarger and print it. Get to first base first. Then AFTERWARDS figure out what you
want out of the damn Zone System or whatever. Isn't it ironic how the Zone Systems "starts" at the bottom with Zone III or II for some people. So what's below
that? A black hole? Just depends. Some film have guts down there, some don't. Do you want something there or do you not? Where do you even buy grade 2 paper anymore? If you like to make things harder than they need to be, that's you're privilege. But the key to the Zone System is that you place these zones where you want them to be, both in terms of the light distribution of the scene, and the density of the negative. And it will differ with both the film developer and print paper, and even how you print and develop that paper. As long as you don't overdevelop the neg to unmanageable density. Then if you encounter a scene that doesn't fit your little ''N" pigeonhole, you figure out how to change something to squeeze it in. That is based upon the subject luminance range, how you want the tones to separate and all kinds of things. I've sure done my share of densitometer plotting, but don't think I've ever spent a minute of it regarding the Zone System. There are a lot faster ways to learn that.

[macandal]

You read the negatives with a densitometer, not a sensitometer.

Stephen, you are right! I meant to say densitometer. Never used sensitometry in my testing. Of course now I can't edit my post. Moderator: can you please change that word for me? Thanks.

You can find a table of aim densities on page 220 of The Negative. You can also use the curves in Appendix 2 to extrapolate the aim densities.

Stephen, I don't have the book in front of me, but, if I remember correctly, I'm pretty sure those densities are for prints. Otherwise, why is he referring to the different readings for the different enlargers one may use (condenser vs diffuser)? As far as using the curves. I wouldn't even know how to do that, and extrapolate--that's one hell of a word, Stephen.

Why don't you read the edge of the film for the fb+f?

I didn't think of that. Thanks Stephen.

And thank you for bringing the thread back to its original question.

[Leigh]

... in the handouts from that class, I can't find what the densities are supposed to be. All I can find are what the densities are supposed to be on a print/enlargement.
I also checked The Negative and AA only gives the densities for the print--not the negatives.

That's because the print is all that matters.

There are many factors affecting the translation of negative densities to final print densities, not the least of which being choice of paper and developer. You must tailor the negative to match.

As I've mentioned numerous times, ZS is a SYSTEM, not a chinese menu.
You can't pick and choose items to use or not use.

- Leigh

[Bill Burk]

I'm seeing very steep average gradients here. 12 minutes is not the right time for Mario to develop for Normal. In fact, this explains the Exposure Index of 160 as well. Even I get Exposure Index of 160 when I develop 100 speed film to average gradient of 1.07

[tgtaylor]

As long as you don't overdevelop the neg to unmanageable density.

But if you do, then print it as a salt print.

Thomas

[Stephen Benskin]

Bill, my calculations came out with a slightly lower number, but not significantly. The 85% development came out around 0.82. Something is not right here. Everything seems to the same as the first test and that seemed close to normal processing. The Ilford development chart has 12 minutes for the processing. Unless the developer wasn't diluted, I can't imagine how the processing can be that off for the stated times.

This is actually helping to make my point about how little useful information this type of testing yields. There can be a dozen possible errors, but there's no way to valid the procedures and pin down the problem. How do we know if the stated Luminance range is the actual luminance range tested? My guess is that the luminance range is larger than Δ1.50 log-H. Good testing should limit the number of variables and control the ones that remain.

The OP may not be ready to realize it but what I'm talking about is a part of the point. Accurate information from good testing.

[Stephen Benskin]

It’s impossible for the Zone System testing method and Kodak’s (tone reproduction theory) to have almost identical subject Luminance ranges as well as almost identical gradients for normal development and produce different negative density ranges. You have the same input and the same processing, the output is going to be the same.

Bill has already given the answer away. Between the subject and the film is the camera, and any optical system has flare or more specifically veiling flare. The amount of flare varies depending on a number of conditions, but in general flare produces an overall non-image forming exposure that is added to the camera exposure. The shadows are affected the most with practically no appreciable change in the highlights.

What flare does is to effectively reduce the subject Luminance range as seen by the film. Average flare for an average scene is around 1 to 1 1/3 stops. To calculate the effective illuminance range striking the film, simply subtract the value of flare from the subject Luminance range.

A 7 stop scene Luminance range minus a stop of flare means the film is only seeing a 6 stop illuminance range. (You can see this in the Kodak’s diagram in post #76.) Let’s also use the three quadrant example from earlier. Reduce the range from I to VIII to I to VII and check what happens to the NDR. It’s now 1.06. A one stop value of flare means you are processing for a 6 stop range even though the original subject is 7 stops. While the diagram illustrates the reduced illuminance range that strikes the film, flare accomplishes it differently than shown.



Kodak’s factors in flare to their equation. NDR / (Subject Luminance Range – flare). Kodak uses 1 1/3 stops flare for the statistically average 2.20 Luminance range or

1.05 / (2.20 – 0.40) = 0.58

[Leigh]

It’s impossible for the Zone System testing method and Kodak’s (tone reproduction theory) to have almost identical subject Luminance ranges as well as almost identical gradients for normal development and produce different negative density ranges. You have the same input and the same processing, the output is going to be the same.

Too much book larnin', not enough practical experience.

Have you ever taken any real (non-digital) pictures, and done any processing?

Although the results should be similar, there's absolutely no justification to assume that they would match.

Both systems have huge variables in metering technique and accuracy, and in the selection of film, film developer, paper, paper developer, the tolerances in all those, accuracy of temperature control, agitation method, etc.

All the discussions I've heard/read over the years treat things like film speed and developer activity as though they were absolute inflexible aspects of the process, when in fact nothing could be further from the truth.

- Leigh

[Leigh]

You're just making a cheap ad hominem attack.
You can't argue with my statements, so you attack the person making it.

You've not mentioned the subject of tolerances, as I stated previously:

Both systems have huge variables in metering technique and accuracy, and in the selection of film, film developer, paper, paper developer, the tolerances in all those, accuracy of temperature control, agitation method, etc.

How does that qualify as an ad hominem attack?

The main goal of "personal testing" as advocated for the ZS is to minimize the effect of those variables.

Kodak notes on their datasheets that the values presented are just starting points, subject to adjustment by individual users. They're not cast in stone. They're valid only for processes that exactly match Kodak's.

- Leigh