Methodology and Curve Interpretation

[Bill Burk]

They were real photos like this scene I am obsessed with … “Willow Pond”

126 scenes classified in five groups: 1. Distant landscapes and marines with no object of interest in the foreground. 2. Objects of interest nearer the camera so haze is less important. 3. Scenes generally photographed like people, gardens and houses. 4. Practically identical to 3 but subject is in open shade while the scene is sunlit. 5. Photographs taken under hazy, light clouds or heavy clouds

 

[Stephen Benskin]

When Jones was doing the "First Excellent Print" tests, what were the photographs of? Was it test charts, like a Kodak grey scale, or was was it real subjects like landscapes and portraits? I'm just curious what those viewers were observing and if that would have affected their reactions.

You can find it extensively covered in the Jones, L.A., and Condit, H.R., The Brightness Scale of Exterior Scenes and the Computation of Correct Photographic Exposure, JOSA, Vol 31, N, 11, 1941. According to Jones in another paper from1951, "126 exterior scenes were given. These measurements were made at different hours of the day and were well distributed through a period of eighteen months. While the majority of these scenes were photographed under clear sunny conditions, a goodly proportion were photographed under other atmospheric conditions, such as haze, light cloud, heavy cloud, etc. Scenes were chosen at random in order to obtain a fairly definitive idea of the range in luminance scale encountered under normal exterior conditions. Since the publication mentioned, luminance measurements have been made on an additional 94 scenes."

The judges had a range of of experience from expert to amateur. They were asked to rate the series of prints for each scene in order of quality.

Resulting in:

 

[aparat]

When Jones was doing the "First Excellent Print" tests, what were the photographs of? Was it test charts, like a Kodak grey scale, or was was it real subjects like landscapes and portraits? I'm just curious what those viewers were observing and if that would have affected their reactions.

I will also add that the studies Jones did were not done an a scientific vacuum, even though he was certainly a pioneer. Other physicists at the time were working to develop quantitative methods and instrumentation to study human perception, which eventually resulted in the establishment of new areas of scientific inquiry. The concepts such as "just noticeable" and "first excellent" were devised to identify and study the limits of perception. In auditory perception, for instance, some of the seminal work was first done by Helmholtz, and later, by physicists at Bell Labs (e.g., Harvey Fletcher). If you read those early papers on sound perception and hearing (1920s - 1950s), some of them read much like Jones's work in terms of the overall approach, the pioneering use of statistical modeling, the inventions of new instruments (e.g., an audiometer and a sensitometer), the use of statistical psychometric methods, etc. I think it's not too far fetched to think of Bell Labs as Kodak's counterpart in hearing research and the Journal of the Acoustical Society of America as the counterpart of the Journal of the Optical Society of America. Kodak and Bell Labs still exist, sort of, but have lost some of their former glory, but the two journals are still going strong.

Even though Jones's studies (and those by others at Kodak) were done a long time ago, published in journals long forgotten (with some exceptions), they deserve to be read and referenced today, in my opinion. It's unfortunate that some of the later sources barely mentioned the early work and, instead, tried to come up with something they considered to be new and improved, but which sometimes ended up causing more confusion than shedding any new light on the issues at hand.

 

[Craig]

Thanks! An interesting way of validating their data on something that seems very difficult to quantify. Although I suppose the problem is there is an addition variable in the skill of the printer. One negative can produce very different prints, depending on who printed it and how.

 

[aparat]

Thanks! An interesting way of validating their data on something that seems very difficult to quantify. Although I suppose the problem is there is an addition variable in the skill of the printer. One negative can produce very different prints, depending on who printed it and how.

Yes, there's always going to be that subjective factor, i.e., the skill of the printer involved in most realistic printing scenarios. However, that's not how the study was done. The scientific method in empirical research of that era was to try to control all possible factors, by either eliminating them or keeping them constant. This allowed them to focus only on one variable of interest, namely, print quality. For example, projection printing was rejected because it would introduce additional sources of variability, such as optical flare and collimated light. The prints were not made by a human being, but rather by a device they built for the purpose. All of that was done to eliminate subjective or highly variable factors, such as the skill or artistic intent of the printer. Here's a picture of the contact printer they constructed:

The only subjective factor as far as I can tell was the operator's choice of paper contrast: "the operator made a careful estimate, based upon his considerable experience in this field, of the paper contrast most likely to give a pleasing print." By employing a lot of advanced data reduction, tone reproduction, and numerical analysis (at least for the era), they were able to offer nuanced quantification of the contributing factors to excellent print quality and, in their own words: "to arrive at relatively simple relationships which might be expected to apply in general." In other words, answering the question of "why is this print of first-choice quality?" was not about asking the judges about their subjective, aesthetic choices and preferences, but, rather by identifying and quantifying these generalizable relationships. Today, this sounds like a very basic aspect of the scientific method, but back in the 1940s, in behavioral research, this would have been considered a relatively modern approach.

 

[ic-racer]

Nice find, I had not seen that diagram before.

 

[Craig]

That's a very clever printing apparatus!

 

[aparat]

Speaking of cool images and apparatuses, here's a picture I find fascinating. The caption and the haircuts say it all:

At a Sensitometric Lab by Nick Mazur, on Flickr

 

[ic-racer]

Two professions gone.
1) The skilled worker's jobs depicted in the photograph
2) The job of the "Industiral/Commercial" photographer, who took the picture (those who subscribed to "Photo Methods for Industry")

 

[Bill Burk]

The Eastman 5222 fell short of ASA parameters in 12 minutes D-76 1:1 but shows full speed 250.

I ended up developing real negatives in this batch instead of verifying development time before developing important shots.

A little bit of remorse because I would have liked more contrast. But I think the pictures will be alright.

 

[Mikolaj]

I am inching closer and closer to the early alpha version of my app. There's still a lot of work remaining, not the least of which is picking the features for the first release. My plan is to make the first release rather basic, just so I can get a feel for what people like and dislike about it. If I find that there's some interest, I will continuing adding more features. I have no big plans, or anything. I just want to share my work, that's all. It may be that nobody cares, and that's okay with me. Writing this thing has allowed me to learn a lot about analog photography. I am not a sensitometrist, or even a physicist, so I had to learn all of that stuff virtually from scratch.

Is there any progress with your software? It looks very nice, and I can't wait to start playing with it

 

[ic-racer]

I'm making some film curves now and wonder if the software discussed in this thread is available yet.

 

[Mikolaj]

Are you still with us?

 

[reneboehmer]

Hey, if you are still looking: https://analogworkshops.at/plotter.html
I made a similar tool, and It's free to use and online. All the best.

 

[benjiboy]

Stephen Benskin:
I’ve been thinking about writing a post on methodology and the interpretation of a film curve when the thread it was for seems to have stalled. So I’ve decided to start a new thread on the topic instead.
Two of the most useful pieces of information that is generally derived from a film curve are film speed and contrast. I’m going to be addressing contrast. According to Contrast Measurement of Black and White Negative Materials, The British Journal of Photography, May 12, 1967, author either not listed or not copied, “
“Contrast measurements provide a practical guide to the photographer by enabling him to choose a development time for a given film in a given developer which will produce a negative suitable for his particular enlarger on his particular paper grade.”
“There are two basic ways of assessing contrast:
1. By measuring the slope of the straight line portion of the characteristic curve (gamma).
2. By measuring the average slope of the part of the characteristic curve that is most likely to be used in practice.”
While most manufacturers use some form of average gradient today, I believe that taking a look at gamma will help to emphasize the importance of using the method of interpreting a film curve that best comports to reality and real world results. The premise on gamma in C.J. Niederpruem, C.N. Nelson, and J.A.C. Yule, Contrast Index, Photographic Science and Engineering, Vol 10, 1966, is that gamma “is not always an appropriate basis for selecting proper development times for photographic for photographic films. It often fails when applied to films for which the D-log E curve have unusually long or unusually short toes because it does not take into account the fact that a portion of the toe of the curve is normally involved in the exposure of a typical negative.”
Here is how gamma, γ, is derived:
View attachment 298315
Next is an example of two films. Film B has a longer toe than Film A, but both curves meet at the same point representing the log exposure range of the camera image. This means that while the shape of each curve will produce prints differing in local tone reproduction, the prints will have the same reflection density range, or in other words, both will fit on the same grade of paper. In the example, however, they have different values for gamma.
View attachment 298318
Taking this as step further, the next example has gamma – time curves and contrast index – time curves (an average gradient method) for a medium toed and long toed emulsion. The development times for two films in the gamma – time curve that will produce films with the same gamma have relatively similar development times. In fact, the gammas are rather closely related throughout development. In stark contract is are the contrast index curves derived from the same family of curves as the gamma – time curve. It shows a far greater difference in development time need to produced negatives with the same contrast index. The paper also includes pictorial examples illustrating the differences.
View attachment 298317
Among the major film manufacturers, I believe only Agfa uses gamma and it is a modified version at that.
In a following post, I plan on reviewing the different average gradients. The distinction with average gradient comes with determining the best method when taking into consideration conditions differing from the statistical average.
Stephen
Life's too short to worry about such things, I just try to shoot good pictures. I don't think many of the photographers who are considered great today did either.