Azo & 3-D effect - Urban Legend?

This has been a fascinating thread. I think it is important to clarify exactly what is meant by 3D effect. As has been mentioned, there are numerous ways to create the impression of depth on a two dimensional image that artists have known for centuries. True stereopsis, however, requires the use of both eyes, each eye seeing a similar, but slightly disparate image from the other eye. So, if the 3D effect that people describe here does not require the use of both eyes it does not represent true stereopsis. If the effect is present only with both eyes, then it raises the very interesting question of how the illusion of stereopsis can be created on a flat, two diminisional image, more specifically, raising the question of what is different about the images seen with each eye. I suspect that what people are describing is not true stereopsis, but something about the print that emphasizes various monocular clues.

One thing that occurs to me is that AZO paper is used primarily for contact printing negatives made with large format cameras. Because of the physical constraints of large format, there is some bias towards wider angle lenses giving the so called wide angle perspective which may emphasize depth in a different way from longer focal length lenses. Large format cameras can also manipulate perspective with shifts, swings and tilts. Both of these features of large format may combine to enhance the perception of depth in a way that is not often seen with smaller formats.

Kirk Keyes said:

Jed, how did you do that? Rotary processing or continuous agitation? How can you be on APUG and not be a believer in any of the multitudes of stand, semistand or whatever the latest variation of minimal agitation techniques are called?

While I'm not sure you can completely get rid of all edge effects, you certainly can do things to minimize the formation of them.

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I published it quite some time ago on APUG as a set of high definition developers. The agitation has been described there too.

Jed

Anyway, I find that perspective is important to the feeling of depth. The viewpoint for seeing the scene in proper perspective through the print is a function of focal length of the camera lens, size of the negative, and magnification between negative and print. Ultimately, one should be able to find a viewing distance where the feeling of depth is maximized. We can't hang it all on resolution and/or contrast, or there would be few works of great painters that gave a feeling of depth.[/QUOTE]

Patrick:
You have to distinguish between depth and distance. The renaissance painters before Leonardo used the central perspective (depth). Leonardo introduced the aerial perspective (distance) and then the two types of perspectives came into the paintings. The aerial perspective , which is a physical phenomenon is the most important one; but hardly noticed while it so common. It is important in photography, and not just for 3_D effects. The scattering of light in the atmosphere determines the quality of light. And that is possibly the most important fact in photography.

Jed

One thing that occurs to me is that AZO paper is used primarily for contact printing negatives made with large format cameras. Because of the physical constraints of large format, there is some bias towards wider angle lenses giving the so called wide angle perspective which may emphasize depth in a different way from longer focal length lenses. Large format cameras can also manipulate perspective with shifts, swings and tilts. Both of these features of large format may combine to enhance the perception of depth in a way that is not often seen with smaller formats.[/QUOTE]

Large format cameras can manipulate central perspective with shifts, swings and tilts. Moreover, it is easier to 'reproduce' aerial perspective with a large format camera than a smaller size camera. Now, if you let work both kinds of perspective together, the effect is optimal. Actually, this is what the painters were doing for centuries ( using Leonardo's manual).

Jed

Another thing occurs to me is that people who use AZO paper are probably fairly skilled at film exposure, film developing and print exposure and development, perhaps more than your average photographer. When all of these are right and printed on a high quality paper with the Dmax, the tonal separation and characteristic curve of AZO, then any monocular clues of depth may be maximized.

gainer said:

The trouble I have with the Criss data is that only a single line is used. A very different result can be obtained when a picket fence type of target is used. A fence of 10 micron lines separated by 10 micron spaces at the film plane would only show a blur with most lenses we can afford. There are not only edge effects but adjacency effects, some optical and others chemical.

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Patrick;

The data in the Kriss report is derived from 3 sets of 21 line exposures to white light and to X-rays. So it is a matrix of 3 x 2 x 21 of which only one set of 3 lines is shown, but the curves from all white light exposures (3 x 21) are used to construct the H&D curves.

PE

John Bond said:

Another thing occurs to me is that people who use AZO paper are probably fairly skilled at film exposure, film developing and print exposure and development, perhaps more than your average photographer. When all of these are right and printed on a high quality paper with the Dmax, the tonal separation and characteristic curve of AZO, then any monocular clues of depth may be maximized.

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I have seen several really nice prints on Azo, but I have seen many prints on Azo that were just outright poor prints. And many papers have a higher D-max than Azo. So I'm not convinced those properties are important.

The characteristic curve is notable in Azo, compared to many other papers available these days.

Kirk Keyes said:

I have seen several really nice prints on Azo, but I have seen many prints on Azo that were just outright poor prints. And many papers have a higher D-max than Azo. So I'm not convinced those properties are important.

The characteristic curve is notable in Azo, compared to many other papers available these days.

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Kirk;

I have all of the curves here. I'll have to normalize them and post them someday. Basically, Azo is not unusual and is rather low in Dmax and contrast compared to some. Not remarkable.

See my post on byegone products. We had 16 samples of all Azo products from EK to examine today.

PE

Photo Engineer said:

Patrick;

The data in the Kriss report is derived from 3 sets of 21 line exposures to white light and to X-rays. So it is a matrix of 3 x 2 x 21 of which only one set of 3 lines is shown, but the curves from all white light exposures (3 x 21) are used to construct the H&D curves.

PE

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I not sure that addresses my point. Are these 3 sets each a set of 21 lines of the same width grouped so as to have the same white space between lines as the width of the line? The narrowest line in the illustration did not look like it came from that sort of arrangement. Certainly the foot of it would have overlapped the foot of its neighbor on each side.

I'm not questioning the validity of such a test. I'm just not sure it's valid for the conclusion reached. Do you know if the same kind of result is obtained with ascorbic acid as one of the developer ingredients? Tell me again where I can see the entire original report for myself.

Patrick;

One set is 21 points at one width, another is 21 points at another width and the third is of course 21 points at another width so 3 x 21. The check developer was Elon + Ascorbic acid. This was first described IIRC, by Pontius and Willis in the relevant photo journals.

This was extended to color by Jim Bartleson and Ed Breneman ( http://www.amazon.com/Bartleson-Breneman-brightness-equation-GARC-report/dp/B000726IGG ) Leroy DeMarsh, and a lot of others.

It addresses your point exactly!

PE

Gentlemen;

I have been thinking this over.

When working on color negative film, very other week I used to run a coating set of Gold 400 which had on average 10 variations in structure. Every set got a complete testing of RMSG and MTF. The MTF used the methods described earlier here by Kriss. Mike and I were good frends, and worked together on this type of thing. In addition, Jim Bartleson, who did many modeling scenarios for EK was a good freind until his untimely death about 10 years ago.

Having had hard data in hand, which supported both of my friends research, I find it difficult to accept that qualitative 'eyeball' data is good enough. In addition, the finest developers designed by Pontius and Willis were used to test these theories.

I find it difficult to accept the fact that someone can make a simple allegation that purports to refute pages nay, reams of scientific effort. It is like saying that the manned landing on the moon was faked. I've been sitting here thinking over the criticisms leveled at this body of work and I just cannot believe that anyone who purports to be an engineer can ignore data from actual experts in the field.

Sorry for the rant. I'm just getting tired of this! I apologize. A lot of people think that they are Photo Engineers but have no credentials. We talked about this at our 4 hour lunch today AAMOF. That is why I am sensitive right now. There were 8 of us there and only 3 of us are on APUG regularly. The rest disdain coming here due to the level of engineering competence displayed in the photographic arena.

PE

Photo Engineer said:

Gentlemen;

I have been thinking this over.

When working on color negative film, very other week I used to run a coating set of Gold 400 which had on average 10 variations in structure. Every set got a complete testing of RMSG and MTF. The MTF used the methods described earlier here by Kriss. Mike and I were good frends, and worked together on this type of thing. In addition, Jim Bartleson, who did many modeling scenarios for EK was a good freind until his untimely death about 10 years ago.

Having had hard data in hand, which supported both of my friends research, I find it difficult to accept that qualitative 'eyeball' data is good enough. In addition, the finest developers designed by Pontius and Willis were used to test these theories.

I find it difficult to accept the fact that someone can make a simple allegation that purports to refute pages nay, reams of scientific effort. It is like saying that the manned landing on the moon was faked. I've been sitting here thinking over the criticisms leveled at this body of work and I just cannot believe that anyone who purports to be an engineer can ignore data from actual experts in the field.

Sorry for the rant. I'm just getting tired of this! I apologize. A lot of people think that they are Photo Engineers but have no credentials. We talked about this at our 4 hour lunch today AAMOF. That is why I am sensitive right now. There were 8 of us there and only 3 of us are on APUG regularly. The rest disdain coming here due to the level of engineering competence displayed in the photographic arena.

PE

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I'm sure you are referring to me. I fear you do not have the slightest idea what I am trying without success to find out from my questions. I have reviewed and commented on more kinds of scientific data than you have ever seen. I know the proper methods of disseminating those data, and your approach is not among them. Your idea that I dare not suggest that you could be mistaken about some line of reasoning because you have been to see the Wizard is not an approach that we would have tolerated at NASA. A degree in any field of whatever level is nothing more than a license to learn. I got my license to learn the minute I was hired by NACA, and applied it to learning flight research methods that were not taught in school and making improvements to them. I learned things about photography that I needed for my job. I learned psychology for the same reason. I studied human transfer functions and made chenges in the applicable theory. I became the principal oboist of the both the Norfolk Norfolk Symphony and the Peninsula symphony as well as a guest artist at the Governor's Palace in Colonial Williamsburg. How? I read some books. I experimented. You see, it was the custom at NACA-NASA to assign an interdisciplinary group to any large project. It was the obligation of each member of the group to learn what the others were doing and to teach others in return. If we at APUG cannot do that, we should not call ourselves the Analog Photograhy Users' Group.

Patrick;

I do not say that you think I am mistaken, I feel you are not understanding the work that I have quoted and that you are claiming they are mistaken. See your comment above about the data being based on one line width. It is clear that you didn't understand what Kriss has reported.

The last time I appeared to criticize you, you gave us a litany of your credentials, and I (much to my normal dislike of doing so) responded with a list of my credentials. Here you go again. I am not going to repeat my former digression. I just don't feel that insecure or upset. I'll say this. I have done the coating and lab work to prove the elements of the work by Kriss, and others at EK and Fuji and Ilford have done much the same. Kriss' work stands and I had the data to back it up. You have not done anything resembling this type of work.

After analysis of his work, and the comments here, I say again that I don't believe that the effect is film alone but is a combination of film, film size, process, print size and viewing conditions. The reasons for this combine factors related to macro and micro contrast and edge effects in my opinion (see comments by myself and Jed above).

This thread was discussed at length by some pretty good photo engineers yesterday at lunch. I learned there that it also has to do with the focal length of LF cameras related to perspective which is one aspect that I had not considered. I also learned that the human eye is a poor second in this type of evaluation due to the variability of interpretation. About the best it can do is tend to verify what the data shows us.

PE

This is a very interesting web site discussing some of the topics mentioned here.


http://psych.hanover.edu/krantz/art/index.html

John;

Thanks for that reference.

I saw a demonstration of this in the 70s by Edwin Land at a conference. He showed full stero images on a flat screen using the dot method described on the first page of that article.

PE

Photo Engineer said:

Patrick;

I do not say that you think I am mistaken, I feel you are not understanding the work that I have quoted and that you are claiming they are mistaken. See your comment above about the data being based on one line width. It is clear that you didn't understand what Kriss has reported.

The last time I appeared to criticize you, you gave us a litany of your credentials, and I (much to my normal dislike of doing so) responded with a list of my credentials. Here you go again. I am not going to repeat my former digression. I just don't feel that insecure or upset. I'll say this. I have done the coating and lab work to prove the elements of the work by Kriss, and others at EK and Fuji and Ilford have done much the same. Kriss' work stands and I had the data to back it up. You have not done anything resembling this type of work.

After analysis of his work, and the comments here, I say again that I don't believe that the effect is film alone but is a combination of film, film size, process, print size and viewing conditions. The reasons for this combine factors related to macro and micro contrast and edge effects in my opinion (see comments by myself and Jed above).

This thread was discussed at length by some pretty good photo engineers yesterday at lunch. I learned there that it also has to do with the focal length of LF cameras related to perspective which is one aspect that I had not considered. I also learned that the human eye is a poor second in this type of evaluation due to the variability of interpretation. About the best it can do is tend to verify what the data shows us.

PE

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I couldn't say whether or not I understood it. I never saw the original. You wold be amazed at how many hits one gets with Google on the name "Kriss", and Pontius too, as you might imagine. What I really wanted to know was if the trace you presented, copied from his report, was from a single line standing alone or part of a crenelate arrangement. It would certainly make a difference in the interpretation of the experimental results if the target were a single line rather than a more usual resolution target, where the edge effect on one line becomes an adjacency effect on the next. I see a similar comparison of microdensity traces across different line widths in the copy of The Theory.... I have, and it is for single lines. I did not question your integrity or knowledge of photographic science, and I think you should do me the same courtesy. All I requested was some clarification or a place to look for myself. You never did say if the data Kriss saw were from discrete lines far enough apart that adjacency could be neglected or a picket fence arrangement.

I learned there that it also has to do with the focal length of LF cameras related to perspective which is one aspect that I had not considered. I also learned that the human eye is a poor second in this type of evaluation due to the variability of interpretation.

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AHA! Something that none of us here had thought of yet. Perhaps that is another major factor in play.

As for being able to see the effect with the eyes, no, I never can, just by viewing the subject with my normal vision. Looking through the ground glass of the view camera, however, lets me see it to some extent. Perhaps this is one of those little things that makes the view camera enjoyable.

Back again. You have no idea what kind of research I have done involving human vision. I still have no idea what led to the data from Kriss that you quote, nor even what the sample you gave means, because I have not been able to find the original. If you had asked me about the things you learned about human vision from your meeting, I could have given you the answers. I had to know them, as I was involved in designing simulators for research and training. Our eyes cannot see clearly both dots of this : at the same time from normal reading distance. You will scan from one to the other if you want to see if one has a malformity.

We used to say that a specialist is one who learns more and more about less and less until he knows all that is to be known about nothing. I'm sure you are not in that category, nor are you the Key bird, who flies in circles of ever decreasing radius until he sticks his head up his own anus and yells "Key-riminy it's dark in here." Well, I hope SOMEONE is laughing now.

Alex Hawley said:

AHA! Something that none of us here had thought of yet. Perhaps that is another major factor in play.

As for being able to see the effect with the eyes, no, I never can, just by viewing the subject with my normal vision. Looking through the ground glass of the view camera, however, lets me see it to some extent. Perhaps this is one of those little things that makes the view camera enjoyable.

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Alex, one of my associates pointed out to us that the focal length and resultant perspective of an 8x10 camera was almost 1:1 wrt the human eye, whereas at other sizes/formats there were small deviations. The 4x5 and 11x14 being closer to the eye but not as good as the 8x10.

This assumes normal bellows extension.

Therefore, the 8x10 contact print is at exactly the same perspective as the original scene, whereas the 35mm or 120 formats will be off by a hair.

Of course, he also agreed that micro and macro contrast were involved in this as well as I had suspected and as Jed had commented on above.

PE

Patrick;

The data from Kriss that I posted show 3 different size line traces at one exposure level. He made 3 different line exposures at 21 different exposure levels to contstruct the curves that are shown. This is what I normally did testing a film emulsion. So, it is a set of 3 21 step H&D curves constructed from micro line and macro line exposures.

If it was done in color, then it was in 3 colors as well.

PE

I learned there that it also has to do with the focal length of LF cameras related to perspective which is one aspect that I had not considered. I also learned that the human eye is a poor second in this type of evaluation due to the variability of interpretation. About the best it can do is tend to verify what the data shows us.

PE[/QUOTE]

I would like to address the two items, you are referring to.

The limitation of the human eye is an important factor.
By choosing the proper photographic procedure, one can identify more details in a landscape than one can do just with your own eyes in the same landscape. We did that, and from the result we got a better insight in the behaviour of the aerial perspective ( the result af light scattering and atmospheric constituents). Since the '3-D effect' in a landscape is the result of the two types of perspective, we were able to get a better feel for what is going on in this process of 3-D viewing. But, I won't say I fully understand all details. I know, it works in the final photographic image and that is where we are after.

Now the first remark on the focal length with LF cameras. First of all, the appearance due to the central perspective will differ with different focal lengths. But, in addition, in our study on aerial perspective, the effect of the aerial perspective is optimal when the camera adjustment is such that the focal plane is horizontal. The reason is that most atmospheric constituents are in the lowest atmospheric layer. And the light scattering will be in that horizontal layer. By focussing along that layer will show the effects of the light scattering optimal. Moreover, the eye usually follows such a focal plane.

Jed

To find all miracles at once, is to much work. Some old-known details:

1. Lenses
30 years ago, I let mount a 300mm Dagor Berlin to a Sinarboard for an artphotographer, using this lens for important impressionist paintings and drawings. Why? Lf-optics of this time showed high contrast in small areas and the ?to much edge-effects? colourfilms of this time will show from a fine and finer getting line to zero a brutal stop of this before zero. With a little less contrasty Dagor Berlin, this fine line runs out to zero, like in the original drawing. The summary of ?edge effects? from optics and film had been not so heavy as usual.

I do not know the effects of lf-colourfilms today.

2. relief
The surface of a negative is important. Patents had been taken on this, because a flat surface without relief (from the swollen and dryed gelatine) show more details on the screen in the cinema. Minox took their impressive enlargements on Photokina in the 50th's from in canadabalsam embedded negatives. Cine-industry (lets say) repolish the surface to enhance sharpness.

When you copy in contact a normal negative WITH usual relief on to paper IN VACUUM, then no resolution-minimizing air (refractive index) is between GELATINE TOO GELATINE (when their two refractive index is equal).
When you enlarge, air is between your film and paper and the relief will show its reducing sharpness influence. Of course you can use scanfluid or so.

Important for contact-printers: Use VACUUM, only glas-pressure is not enough.

I have written a 3 page text in german on 8.may 2003 about Auflösungsvermögen und Brechungsindex (engl.: Resolution and refractive index) on my website, all this is mentioned there.

3. individuell seeing
Looking to whole field of science, at first you must look to the individuum itself. Every human see a little bit different, and the data-connecting of the eye-signals is different. Next is measuring from institutes, national or global, all sensual aspects in feeling, here in Germany is this done by www.grp.de since 40 years all 5 years with 4000 people. The results show a intensiv change in the feeling of viewing - anything you see gets a more importance, the ethic values from your memory will not asked more than in earlier times.

4. prognosting effects in 3-d in 2003
Looking to whole field of science, at last you mention to see in 3-d a quality, this is mentioned in the text "Für ein neues Photopapier" -for a new photopaper- from 4. jan. 2003. Anything, people is mentioned here on this forum in seeing differences in a better paper, all about the subtil mechanism of unconscious, there it is in german, but for these, who want to read the original, look to /download/neues_photopapier.pdf on

http://www.gigabitfilm.de/html/deutsch/anwendung/wissenschaft/chemie/chemie.php?Layout=normal

Any better paper is welcome!! For a better photography!

Kirk Keyes said:

I'm skeptical of this so-called "3-D" effect that people report that Azo has. Perhaps it's an optical illusion that some peoples brains process, and others can't.

Let me hear your anecdotal stories and convince me one way or the other.

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OK, we've dived into the bottomless well of technical fine hair splitting. Has the original question been answered one way or another?

Alex Hawley said:

OK, we've dived into the bottomless well of technical fine hair splitting. Has the original question been answered one way or another?

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There are many aspects on 3-D ( e.g. depth perception and distance perception). Google on this subject and you will get much information. Information that will depend on the subject ( a landscape or a portrait are different in their approach). I think, we are not going to repeat this at this site.
Here at the APUG site, we are discussing the 'technical apects' of the photographic process, related to the 3-D effect. What is applicable where, depends on the situation and on the human interpretation.
A similar approach on 3-D can be found in the literature on painting.

Jed

Alex Hawley said:

OK, we've dived into the bottomless well of technical fine hair splitting. Has the original question been answered one way or another?

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I think the possible causes of 3-D have been examined in a general way. And it appears that there are a few reports of other papers being capable of causing such illusions.

As far as the urban legend part, I think that is still up in the air other than one comment that Azo is a rather unremarkable paper when compared to other papers.