Pyrocathecol, catechol age
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Jed,
I found the articles and see that different conclusions might be obtained, but do not know for certain if the addition of the second agent, phenidone, metol or p-aminophenol, could be the cause. If so, ther is some kind of stain superadditivity going on. You could use metol alone in any concentration you want and not get a stain. Same goes for p-aminophenol (Rodinal for example).
The Pyrocat series was specifically meant to be used with printing processes that require high contrast and are not sensitive to much above UV, but yet can be printed on conventional papers. You might try hydroquinone in place of catechol in your single agent developer. I will certainly do so at my first opportunity. I do know that a developer using hydroquinone in place of the catechol in Pyrocat MC gives a very visible reddish stain image.
I found the articles and see that different conclusions might be obtained, but do not know for certain if the addition of the second agent, phenidone, metol or p-aminophenol, could be the cause. If so, ther is some kind of stain superadditivity going on. You could use metol alone in any concentration you want and not get a stain. Same goes for p-aminophenol (Rodinal for example).
The Pyrocat series was specifically meant to be used with printing processes that require high contrast and are not sensitive to much above UV, but yet can be printed on conventional papers. You might try hydroquinone in place of catechol in your single agent developer. I will certainly do so at my first opportunity. I do know that a developer using hydroquinone in place of the catechol in Pyrocat MC gives a very visible reddish stain image.
And there is yet another issue. Microscopic inspection will not indicate exactly how the negative will print because the eye is not nearly as blue sensitive as photographic paper. For the same reason comparisons of sharpness might also be suspect if evaluated by eye with a microscope, unless approprate filtration is used.
I think you would get a much more accurate indication of real printing values and sharpness if you were to view the negative with the miscroscope through a blue filter, such as a 47 or 47b.
Sandy King
Gainer,
[Hydrochinon will not work; it works in the superadditivity construction].
I designed the pyrogallol HD and the catechol HD for use in medium and large format applications. So, we are back before 1926, when the 35 mm film ( and fine grain developer D 76) was introduced. I think, the 35 mm will be replaced by digital photography. In that case, the situation before 1926 is back again. We can optimize for large and medium format.
Because I wanted to avoid adjacency effects (sometimes useful with 35 mm, but not in the other formats), I came back on the single agent developers pyrogallol HD and the catechol HD, because of their known superior image qualities ( with silver prints).
[Your pyrocat developer is meant for other purposes, so other criteria apply.]
Jed
Hi Sandy:
I wonder, what is the reason of 'more accurate indication of real printing values and sharpness'.
What we need is an image with 'image quality' as seen by a panel. The image quality is determined by the properties and limitations of the human eye, and a variety of photographic parameters and the subject to be photographed. Scientific results are published by a German and a Kodak group. It is physics and psychophysics and unfortunately the average photographer cannot easily read that material. [I am trying to 'translate' this in more plain language].
In a simple way: 'What you get is not what you see'.
My 'translation' will be a little more differentiated and will allow for an optimum image quality through the selection of your 'photographic equipment and procedures'.
Or to say it differently: A landscape on 16x20" will require a different approach than a portrait on 4x5". The question is: how to arrive at an optimum image quality ( as judged by a panel) in both cases.
Jed
Jed,
I am afriad you missed my point altogether. Image quality of the print as judged by the human eye is perfectly acceptable. Indeed, ultimately it is the final and ultimate arbiter.
However, you are trying to predict ultimate print quality by observing with a miscroscope a "negative," but the negative will not print on paper the way your eye sees it because of the different spectral response of the human eye and photographic paper. What your eye sees is much more weighted toward green light, but the paper has greatest sensitivty to blue, and that is true of both graded papers and VC papers.
The difference between the visual response of the eye and the response of paper is not highly relevant when we print with non-stained negatives, but it is very relevant when printing with negatives that have a lot of stain.
Sandy
Sandy:
I think, we have different objectives in mind. I want to avoid ( blurring) stain in a (fine grain) catechol developer from an image quality point of view. Because the stain is usually yellow_green colored, I can visually detect that.
Because the stain is usually yellow_green colored, it has a high transmission density for blue. And is therefore an effective supplement for the optical density of the silver.
In the case of pyrogallol HD, I take advantage of the stain.
You are making a macroscopic sensitometric measurement in blue light, as I understand it. These sensitometric measurements are for macroscopic tonal reproduction purposes ( as described by Nelson in 'The theory of the photographic process' 4 th ed).
So, we are talking on two different subjects; you are talking on macroscopic tonal reproduction and I talk on optimizing image quality (as judged by a human panel).
Jed
.
Jed, I am just trying to understand what you mean by this statement:
Jed
Jed
Jed Freudenthal ...I want to avoid ( blurring) stain in a (fine grain) catechol developer from an image quality point of view... Jed .[/QUOTE said:
Hi Tom:
I can imagine you found a statement from me on catechol stain strange. However, I am saying that catechol developer has NO stain. A catechol developer has a very clean image ( and this is what I find in the literature). I say: catechol has a very clean image; because the fog level is very low. I do not use any restrainer as you know. The prints of a catechol negative are very very clean.
On the contrary, the pyrogallol HD developer has a stain and the grain is masked to some extent. I have many prints to demonstrate this. And just recently, I made a comparative test on one subject ( a landscape) with the catechol HD developer and the pyrogallol HD developer. In the print with a magnification of 4x one can see the blurring effect in the pyrogallol HD developer print. But, I must say, in the pyrogallol HD print, the blurring effect is beautiful, from an artistic point of view. In the pyrogallol case, I am happy with the blur.
Now, when I go to higher magnifications (16x20" prints), the 'clean' catechol prints are usually preferred above the pyrogallol prints ( for landscapes). For other subjects, like portraits, it is different. Therefore, the quality of the final print can be good with or without blur. And much depends on the magnification factor of the print, the photographic subject and conditions like the photographic lens properties etc. But, the details on that can be found in the published papers on photographic image quality ( by Kodak and a German group). At the moment, I am trying to make these publications readable for the average photographer. I hope, I will succeed. I can tell you, it is not easy to 'translate' these publications.
Jed
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Jed, I interpret your statement "I am saying that catechol developer has NO stain." In the following way:
" Jed Freudenthal's catechol developer produces NO IMAGE stain."
Many people have demonstrated that catechol developers which contain low (or no) sodium sulfite and no ascorbic acid or ascorbate DO produce IMAGE STAIN.
The Hans Windisch WATER/CATECHOL/SODIUM SULFITE/SODIUM HYDROXIDE compensating developer is a LOW SULFITE EXAMPLE THAT STAINS (contains 2.5 grams Sodium Sulfite crystals).
" Jed Freudenthal's catechol developer produces NO IMAGE stain."
Many people have demonstrated that catechol developers which contain low (or no) sodium sulfite and no ascorbic acid or ascorbate DO produce IMAGE STAIN.
The Hans Windisch WATER/CATECHOL/SODIUM SULFITE/SODIUM HYDROXIDE compensating developer is a LOW SULFITE EXAMPLE THAT STAINS (contains 2.5 grams Sodium Sulfite crystals).
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If you mean it will not produce an image, you are wrong. The image I got by direct substitution of hydroquinone for catechol in your formula looks as if it could have used another stop of exposure, and the stain is quite faint, but it is there. When I substitute hydroquinone for catechol in Sandy's formula for Pyrocat PC, I get the visible yellow-brown stain and better shadow detail. Others will see different colors. It as a function of age and other factors. I am old enough to have a sort of brown outlook on life, which I try to brighten with a bit of humor.
I am puzzled by your association of objectionable edge effects with superadditive combinations. Have you tried Pyrocat MC or Pyrocat PC? I think I said before that some edge effects are subjective in that they are artifacts of the human visual system. Upon close inspection with a loupe, they disappear and only a sharp, clean edge remains.
My statement is: MY catechol HD developer has no stain. No image and no general stain. The image is, however, brownish colored, because of the fine grain of the silver.
This developer is derived from a sulfite free developer, and has a long history from the 1880's. Dietrich in Talbots "Neuheiten" 1891 is recommending the formula. And in the 20 th century, it has been used frequently by professional photographers.
I do not make any statement on other catechol developers; certainly not on developers with more developing agents.
Hans Windisch formula is also a modification on that very old formula ( the alkali differs). Hans Windisch does not mentione any stain, but the brownish color of the silver deposit.
You mentione that many people have demonstrated image stain in low/no sulfite catechol developers. I would like to see these publications. Can you give some references.
Jed
Gadget:
I understand you substituted the catechol in my formula for hydrochinon. I never did that, but the literature says: 'the density is low'. I understand that your observation iis in agreement what I have from the literature. You mentione a stain that is quite faint. Is this an image stain? Is it with catechol or hydrochinon? What did you observe with catechol? And was the catechol fresh or already aged?
In a certain period of time, edge effects were accepted in a very positive way. Indeed, they could increase the sharpness, in particular in 35 mm pictures. However, the edge effect was often overdone as a result of a spike at the edge. In microdensitometry this spike can be recorded.
When the edge effect is overdone, people don't like the image anymore; the image quality is down.
In digital imaging, the effect has been simulated and is called 'sharpening up'. By now, one knows to be very careful using the 'sharpening up'. A US firm is selling now software in which the 'sharpening up' is controlled.
At the moment edge effects do not have a positive image anymore. And, with medium and large format one doesn't need them.
I prefer developers without edge effects (or an MTF not peaking above 100%) for medium and large format and normal pictorial work.
A very thorough paper on this subject has been written by C.N. Nelson, (Kodak) Prediction of densities in fine detail in photographic images, Photgraphic Science and Eng. 15, 1, 82-97, 1971. He gives infomation on a range of developers too.
Jed
No problem Jed:
1.Hans Windisch, THE MANUAL OF MODERN PHOTOGRAPHY, page 89
2. Grant Haist, Volume 1, Modern Photographic Processing multiple references.
3. Tom Hoskinson (I recommended this D log E curve to you earlier in this thread):
(there was a url link here which no longer exists)
Jed,
We appear to be having a real problem of communication. Perhaps it is a language problem. However, to be precise, it is not me who is "talking about macroscopic tonal reproduction." You are the one who mentioned that you were using it to evaluate negative sharpness. I merely pointed out that macroscopic tonal inspection of a negatives does not give you a clear indication of image quality on the print. Are you saying that it does? If so, I very much disagree with you.
Sandy King
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I find your discussion of edge effects somewhat confusing. First, you appear to be saying that a developer such as your catechol HD developer that uses only one reducer does not give edge effects, but developers that contain more than one reducer give edge effects? If that is true, it is contrary to my understanding, which is that a single reducer devleoper is more likely to exhaust faster and create edge effects than a developer that contains two reducers.
Second, I don't agree at all with the opinion that edge effects are not necessary or desirable in LF photography. In fact, I am of the opinion that edge effects are at least as desirable in LF negatives, if not more so, than in 35mm and roll film work. This opinion is not based on theory but on close inspection of contact prints made from LF and ULF negatives.
Sandy King
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I certainly agree that overdone edge effects are objectionable. But I also maintain that some edge effects visible to the eye in a sharp photograph are in fact not visible on close examination. We have learned through the evolution of high fidelity audio reproduction that there is no good substitute for true bandwith. Information at higher frequencies folds back onto lower frequencies. A similar effect is obtained when an attempt is made to square up the leading and trailing edges of optical square waves. I have seen examples of over zealous application of the unsharp masking technique which gave the impression of overlaid cardboard cutouts. These are generally independent of the number of developing agents used. You can obtain such effects with Rodinal, which has only a single agent, or D-23, or a variation of Rodinal using Metol in place of p-aminophenol.
I am looking at a print with a sharp edge which appears to have the Mackie line on it sharp edges from normal reading distance. As I move in closer aided by a high quality 5 inch lens, the mackie line disappears. I see no good reason for trying to make the visible Mackie line disappear at the normal viewing distance. Nor do I see any good reason for making the line remain at closer distances. While you are examining images from Pyrocat MC with the microscope, look at the image of the edge of a sharp black line and compare it with the same view of the original sharp black line.
I am looking at a print with a sharp edge which appears to have the Mackie line on it sharp edges from normal reading distance. As I move in closer aided by a high quality 5 inch lens, the mackie line disappears. I see no good reason for trying to make the visible Mackie line disappear at the normal viewing distance. Nor do I see any good reason for making the line remain at closer distances. While you are examining images from Pyrocat MC with the microscope, look at the image of the edge of a sharp black line and compare it with the same view of the original sharp black line.
The edge ( or adjacency) effect can be recorded on a microdensitometer. It will show up as a spike. I was never able to see it with a magnifying glass. But many people (panels) notice these effects, and they experience it as 'objectional image quality' . In the first few seconds there is a 'wow' effect, but pretty soon that reaction will change. On the other hand, for example in 35 mm prints, the effect may work in a positive way. In the last few 'digital' years, digital images were sharpened up like an adjacency effect. Often, probably too much. Anyway people couldn't stand these images and the sharpening up was not used anymore, or with much caution. Very recently, an US firm came up with a computer program, in which the sharpening up would be 'under control'.
Going now back to the analog photography situation. I optimized on the reactions of a panel ( during a ten year period). There was a preference for developers with one developer agent at a relative high concentration ( for middle and large format).
And the agitation was important ( see formula) as is the film type. And the buffering of the alkali. And the film type. Only the FP4+ has signs of some adjacency effect, but the Forte and Adox 100 films, Tri X 320 didn't show that at all. I found this not that surprising because my two formulas are based on old proven formulas. Another example is the good old Rodinal. According to the Agfa MTF data there is no adjacency effect.
But, if I would like to get an adjacency effect, it is no problem to get that. The point is how to avoid it. And, unfortunately, it is difficult to control.
Gadget, you mentioned the analogy with the audio sitution. This is very true. The higher frequencies which are not audible to the human ear, can be heard when they are superimposed on the lower frequencies. The real quality of a violincello is determined by what happens in the high frequency range. The situation with the adjacency effects is very analogous. Just replace the audio frequencies for spatial frequencies. Scientifically, it all is the same.
Jed
Jed Freudenthal; Hans Windisch does not mentione any stain said:
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This is where the modulation transfer function enters. When we deal with an audio recorder, "printer" , playback and human ear, we have much more than a simple addition. I used to know and use the terms when I worked at NASA in Simulation and Human Factors research. There had been a long standing effort to characterize what we called tracking behavior as a linear transfer function of the type tha could be simulated by an electronic network of resistors, insuctors and capacitors. When one tells a student acting as a test subject that he is to behave in such a manner, he can do a pretty good job of it. The random variations, called remnant, were fairly small. When one tells an experienced pilot to perform the same test, the remnant may increase quite a bit, and will depend on the simulated task. Simulated gunnery runs were often more linear than the task of holding a course in air turbulence.
This is mostly beside the present point. My point should have been that the net result of the photographic process is much like a musical recording. Even if we are listening directly to the performance there will be differences between performances in tone quality, articulation, tempo, and dynamic variations, and I expect the same of photographers depicting the same scene. I might express a preference for one over another, and you might prefer a different one.
My instrument was the oboe, which is capable of a wide range of everything. Even though it has been described as the "ill wind that nobody blows good" I found that I could not teach my students only one way to do any one thing. I think the same is true of the camera. If I am to be a teacher, I should show how to get everything out of the camera that is possible, and I should not say that one effect is absolutely the best.
The edge effects we can get are influenced by the camera lens, the film, the developer, the developing technique, the printing method, the printing equipment and the printing materials. Have I left anything out? I think I could take one of your anti-edge-effect developers and use it to produce an edge effect. I think I can take a developer with two or more developing agents and use it to get no visible edge effect. I think if you do a proper job of your research, you will find interesting and valuable facts. I just do not think that the way to go about it is to make assumptions about what causes edge effects and to test only those assumptions. I hope that is not what you are trying to do.
This is mostly beside the present point. My point should have been that the net result of the photographic process is much like a musical recording. Even if we are listening directly to the performance there will be differences between performances in tone quality, articulation, tempo, and dynamic variations, and I expect the same of photographers depicting the same scene. I might express a preference for one over another, and you might prefer a different one.
My instrument was the oboe, which is capable of a wide range of everything. Even though it has been described as the "ill wind that nobody blows good" I found that I could not teach my students only one way to do any one thing. I think the same is true of the camera. If I am to be a teacher, I should show how to get everything out of the camera that is possible, and I should not say that one effect is absolutely the best.
The edge effects we can get are influenced by the camera lens, the film, the developer, the developing technique, the printing method, the printing equipment and the printing materials. Have I left anything out? I think I could take one of your anti-edge-effect developers and use it to produce an edge effect. I think I can take a developer with two or more developing agents and use it to get no visible edge effect. I think if you do a proper job of your research, you will find interesting and valuable facts. I just do not think that the way to go about it is to make assumptions about what causes edge effects and to test only those assumptions. I hope that is not what you are trying to do.
Edge effects
Hi Gadget:
Interesting to see what your background is. My background is physics and chemistry ( applied in the forensic area). After my retirement I found the time to focus, more than before, on human perception. My neighbor (Bouman) was the director of a Simulation and Human Factors research lab at an US-Dutch Soesterberg airbase and the director of an equivalent lab at the University of Utrecht. They used to use MTF for their descriptions of phenomena. They say to use other methods today. They even got rid of their microdensitometers. However, I stick with the MTF approach because it is the common language in the photographic world when it comes to image quality.
I fully agree that edge effects are only part of the story. The properties of lenses, and the rest of photographic procedure are playing an important role. And, do not forget the properties of the human eye. I am trying to write a text on the subject. At least, I am being asked to do that. It is a real challenge.
You might think, that I am a theoretician testing assumptions. That is not the case. I am using the results and recommendations of other research groups on image quality. A German research group had a panel of 4.000 people, when it comes to sharpness! Then I make use of their recommendations in actual photography, and see if it works, using a (smaller) panel. It is very simple, I am a photographer, just using the recommendations of research groups on image quality.
Jed
Hi Gadget:
Interesting to see what your background is. My background is physics and chemistry ( applied in the forensic area). After my retirement I found the time to focus, more than before, on human perception. My neighbor (Bouman) was the director of a Simulation and Human Factors research lab at an US-Dutch Soesterberg airbase and the director of an equivalent lab at the University of Utrecht. They used to use MTF for their descriptions of phenomena. They say to use other methods today. They even got rid of their microdensitometers. However, I stick with the MTF approach because it is the common language in the photographic world when it comes to image quality.
I fully agree that edge effects are only part of the story. The properties of lenses, and the rest of photographic procedure are playing an important role. And, do not forget the properties of the human eye. I am trying to write a text on the subject. At least, I am being asked to do that. It is a real challenge.
You might think, that I am a theoretician testing assumptions. That is not the case. I am using the results and recommendations of other research groups on image quality. A German research group had a panel of 4.000 people, when it comes to sharpness! Then I make use of their recommendations in actual photography, and see if it works, using a (smaller) panel. It is very simple, I am a photographer, just using the recommendations of research groups on image quality.
Jed
Hi Tom:
I am not in the possesion of an english version of the book of Hans Windisch. Most of them are in German, and there are later versions in the Dutch language ( but they are modified by the translater too). In the book, I have, Windisch does mentione the tanning effect and that it cannot be reduced or intensified.
And then I quote: 'the silver deposit is brownish', when I try to translate this accurately.
I get the impression that there might be a change in the text in the translation process.
I was trying to find the spot where Haist is quoting a reference. But was unable to find it. Would you be so kind to give the page in the book of Haist. The quotation can never be from German origin, because the Germans do not have a word like 'staining'. The Germans describe the phenomena they observe.
Jed
Whether you like edge effects or not is a matter of taste. Crawley made developers with a engraving-like appearance. However, for regular pictorial work, many people ( panels) do not like them.
A single reducer developer, with suffucient developing agent, sufficient agitation etc. exhausts usually less than a developer with more agents (but this is very generalized speaking). The effect of an edge effect is, however, reflected in the MTF. Many of that has been published. I have given one reference (Nelson) in this thread already.
Jed
Jed, this is what the 1957 English edition of Han's Windisch's book says: "Owing to the small amount of sodium sulfite used, the developer has a tanning effect, producing negatives of a brownish color."
It appears that this English translation from the German Edition was approved by Windisch.
In any case, IF the "brownish color" Windisch describes was caused by re-deposited silver (as is the case with Kodak's Microdol-X Developer), it should be removable by bleaching (with a ferricyanide bleach).
When I bleach a film developed in Han's Windisch's catechol developer, a tanned, stained, brown image REMAINS - QED
Regarding page references for Grant Haist's statements, comments and quotes on Tanning/Stainining developers; See Haist's Tanning Developer Section which begins on page 507 and continues through page 538 of Volume I, Modern Photographic Processing.
Tom, thank you for this information on the english edition of the book of Hans Windisch. It is not an accurate translation; because Windisch is not talking on a brown negative, but a brown image. And he is not referring to something like stain.
According to your bleaching experiment the brown color is the result of a stain. Then I would conclude it might be a very fine stain. In the past it was thought that the brown color was the result the fine deposition of the silver, as is the idea about the warm color of prints. However, we cannot reject the idea of a very fine stain, considering what has been done in color photography.
May be, there are two origins of the warm color. I would suggest, you inspect your bleached negatives with a microscope and describe your observation. And we have to be sure, the bleaching was 100 % perfect.
With respect to the book of Haist: I can only find stuff on tanning, but nothing on staining. I can agree with the stuff on tanning. But the subject now is staining.
Jed
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