Azo and Amidol

[edbuffaloe]

This new article by Bob Herbst is available at http://unblinkingeye.com/Articles/Azo3/azo3.html. Herbst ran some tests at Dan Smith's request to see how the tonal range of Azo compared with that of platinum/palladium prints, using the test negatives he made for his article on The Effects of Pyro Stain (at http://unblinkingeye.com/Articles/Pyro/pyro.html).

 

[Tom Duffy]

Ed,
Thanks for bringing the article to our attention. among other things, it confirms the good points concerning the Michael Smith Amidol formula.

Having no experience with desitometry or step wedges and the like, a couple of elementry questions: does this indicate that D-76 offers better shadow separation and worse highlight separation than pyro? also it seems to say that pyro offers an ability to capture a longer brightness range (in the scene) than D-76. Do I interpet that right?

Also do you know what film Bob used? My experience with Berrger indicates it is fantastic with pyro but not so good with normal developers such as HC110 and XTOL. I never tried it with D-76 though...

Tom

 

[David Hall]

Ed,

What kind of pyro does Bob use? And does it matter? As you know, Michael Smith is fanatical about ABC pyro, as fanatical as Gordon Hutchings is about PMK pyro. Which was used for the pyro step image he used?

Thanks!

dgh

 

[David Hall]

Ed,

I'm not sure if this is true for others or not, but I am not able to access Bob's pyro stain effect page through the link you provided.

dgh

 

[David A. Goldfarb]

Very useful article, Ed. It quantifies the things that can be quantified, but acknowledges the fact that whatever the density range, Pt/Pd will still have a different look from Azo, because of the surface reflectivity, among other things.

Gordon Hutchings has come around and recently said that ABC is probably better for contact printing on Azo than PMK, because ABC produces a longer scale negative, and the grain masking effect of PMK is not so important for contact prints.

 

[lee]

i had that problem too. go ahead and click on it and then when it tells you you cannot access look up at the address and delete the "close parathenses" and then try enter and that will let you in. Least it did for me.


lee\c

 

[edbuffaloe]

What happened with the link to the pyro article is that the close parenthesis became part of the URL. Here is the URL again: http://unblinkingeye.com/Articles/Pyro/pyro.html.

In response to Tom Duffy's question, I believe pyro offers better tonal separation at both ends of the tonal scale. This is particularly apparent when enlarging--see http://unblinkingeye.com/Articles/Pyro/Fig...4/figure_4.html --but is also evident to a lesser degree when printing with either platinum or Azo.

For these tests Herbst was using negatives developed in his own variant of the Wimberley WD2D formula. It all started with Herbst's article on the use of pyro negatives for platinum printing. He did a comparison that showed clearly that pyro negatives offered a longer printable tonal range for both platinum and silver. Dan Smith and I approached Herbst to run the same test on Azo, since Michael Smith had suggested (somewhere) that Azo might have a longer tonal scale than platinum. Herbst's results show that Azo has at least a nearly equivalent tonal scale, which is a very significant finding. --So much so that Herbst plans to use Azo and amidol for making fine prints in the future, in addition to his platinum work.

 

[Michael A. Smith]

Herbst's article is a great one. My reading of it confirms that while platinum may show more steps than Azo (but just barely) Azo has a far longer visual scale. That must mean that the platinum steps are closer together, which helps give platinum prints the "flat" look they so often have. That combined with the significantly shorter density range of platinum prints supports my contention that prints on Azo have a longer scale than prints on platinum.

Bu some people do prefer the platinum look. Which paper you use should always be a function of how you want your prints to look rather than by the numbers.

Michael A. Smith

 

[David A. Goldfarb]

Just out of curiosity--and this will probably sound like heresy to people who prefer the classic platinum look--what happens if you try to increase the surface reflectivity of a platinum print? Will the emulsion adhere to any glossier papers, or what happens if you spray a high-gloss lacquer on a platinum print (okay, start preparing the stake for the heretics, but Strand varnished his prints, as I'm sure others did in that era)?

 

[avandesande]

I wonder if this perception of scale has to do with the perception of silver particles floating on the top of the clear gelatin emulsion?

I think that platinum seems to favor an image with a certain type of tonal scale, perhaps that could be described as 'long midtones'. Azo/amidol seems to favor images with a prevelance of 'top notes'.
Sorry for the dogy terminology.. talking about photography is always difficult.

--Aaron

 

[edbuffaloe]

In Herbst's tests platinum reproduces 19 steps of the step tablet in a manner that is clearly discernable to the human eye, while Azo reproduces 18. However, the density of the platinum print extends from 0.13 to 1.47 (reflective density range 1.34), whereas the Azo density extends from 0.15 to 1.92 (reflective density range 1.77). The tonal range reproduced is virtually identical, but the reflective range of the Azo is just over two stops greater than the platinum print in this test. The extended reflective range of the Azo is in the blacks, which are much deeper than the blacks in platinum/palladium. However, the high values of the platinum/palladium print have more delicate gradation than the Azo print.

 

[Jorge]

Hmmmm...I don't see why this is any surprise. I have only been printing with pt/pd for a few months and it is clear to me the tonal range is compressed. As a matter of fact it is clearly explained in the Arentz book. The platinum particles are in the paper and as such they "trap" light thus the lower reflectivity. The "flat" prints Michael mention are mainly due to a poor choice of negative rather than the inability of pt/pd to produce luminous prints. Terry King made a comparison of black from a pt.pd print and a silver print and most people thought the pt/pd had "deeper" blacks than the silver print, even thought the D max is only 1.4.
IMO pt/pd is better for high key negatives where the light tones are more important than the shadows, while azo I suspect is better for negatives with a long tonal scale and lots of "grays" where the dark and light tones are used for accent rather than an integral part of the "message".
The prints are very different and should be used for the particular "style" of the photographer. Trying to compare Azo to pt/pd is like comparing apples and oranges, each have their own taste and qualities. To say that either one is "better" or capable of yielding better prints than the other I think is foolish.

I applaud Bob's open mindedness but I really think this was more an exercise in sensitometry than a comparison. What is next? Azo vs POP, or Pt/pd vs Kallitype?

 

[avandesande]

Jorge, it is almost impossible to do a completely 'fair' comparison, I am a just greatful that someone is trying to make some sense of what to this point has been borne out by experience and word of mouth.
Most people will agree that a master of their medium will pick subjects and conditions that suit their process. Not many negatives print equally well on platinum and AZO.

Another thing that has become apparent from this article and the one on pyro stain, is that Pyro expands the scale of the highlights on the negative, which will in turn expand the scale on the print. This probably helps AZO achieve the long scale look, especially in the highlights.

 

[edbuffaloe]

I think it is always useful to have hard data rather than someone's subjective impression. I love the look of platinum/palladium, and there are certain subjects for which it is the perfect medium. The same is true for Azo.

In regard to the D-max of platinum, there was a recent post on the Bostick & Sullivan forum regarding Mars All-Purpose Translucent Vellum paper. It is said to have excellent wet strength and to give significantly better blacks than other papers. There was speculation that the deep blacks are due to its translucent nature, which allows light to penetrate into the depths of the paper.

 

[Kerik]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (edbuffaloe @ Jan 31 2003, 11:07 AM)</td></tr><tr><td id='QUOTE'>I think it is always useful to have hard data rather than someone's subjective impression.&nbsp; I love the look of platinum/palladium, and there are certain subjects for which it is the perfect medium.&nbsp; The same is true for Azo.

In regard to the D-max of platinum, there was a recent post on the Bostick & Sullivan forum regarding Mars All-Purpose Translucent Vellum paper.&nbsp; It is said to have excellent wet strength and to give significantly better blacks than other papers.&nbsp; There was speculation that the deep blacks are due to its translucent nature, which allows light to penetrate into the depths of the paper.</td></tr></table><span class='postcolor'>
I was the one who started the Mars Vellum discussion on the B&S board. After many years of printing platinum I found a paper that happens to produce a startling black. Doesn't mean it's better or worse than the many other papers I use, just different. What's even more exciting about this paper for me are it's ultra-smooth tones, excellent resolution of fine details, and fantastic tonal separation. I don't own a densitometer, so I can't tell you what the reflection density is, but my guess is that it approaches or surpasses the DMax of matt silver gelatin papers. My opinion is that this super deep black comes from a combination of factors: the transluscency of the material, the ultra smooth surface, and the fact that the sensitizer seems to sit way up on top of the paper rather than being absorbed deeper into the fibers that typically happens with more "normal" papers used for platinum.

I agree in general with Jorge that the sensitometric comparison of AZO and platinum is little more than interesting trivia. What is more important to me is how the medium conveys the image and intent of the photographer. I've done lots of printing on AZO with Amidol and Ansco 130 (I still have a few boxes of 14x17 doubleweight AZO in my darkroom). I've also done and continue to do a lot of printing with Centennial POP. My main medium for the last 10+ years has been platinum/palladium. In the last couple of years I've also been adding layers of gum bichromate over platinum for the unique look that those combined processes provide. Through all this printing I have purposely avoided the use of a densitometer because, *for me* that type of analysis is simply a distraction to my main intent which is making really beautiful prints. All of these materials are capable of wonderful results when coupled with the right image and a well-made negative. My preference is for very warm tones and lots of color, so I am much more attracted to platinum, gum over platinum and POP than AZO. Nothing makes me yawn faster than a neutral gray print.

Regarding the question of increasing the surface reflectivity of a platinum print. Strand did it and it is still common practice. I've used wax and acrylic gloss medium to achieve this effect. I've also read of people using Future Floor polish for the same purpose(!) For some papers these treatments make a dramatic change in the appearance of the blacks. As far as getting the sensitizer to stick to a glossier surface, that is a much more difficult problem.

Kerik Kouklis
www.Kerik.com

 

[Jorge]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (avandesande @ Jan 31 2003, 12:39 PM)</td></tr><tr><td id='QUOTE'>
Another thing that has become apparent from this article and the one on pyro stain, is that Pyro expands the scale of the highlights on the negative, which will in turn expand the scale on the print. This probably helps AZO achieve the long scale look, especially in the highlights. </td></tr></table><span class='postcolor'>
Sensitometrically speaking that is incorrect Aaron, and is very well explained in Dr. Henry's book, "controls in black and white". You cannot expand the paper scale, all you can do is fit the negative to the paper range. As Bob explained in his article azo is just better able to accomodate a more contrasty negative than most silver papers. I am not sure that the same cannot be said for other developers which can separate the highlights as well. Azo has a very long scale while pt/pd compresses the scale, this is why very contrasty negatives are used in pt/pd to make up for this compression. The key is to fit the negative to the paper. If anything your statement is better applied to pt/pd than to azo. Although pt/pd is "cramming" more tones in a much shorter scale, it's ability to better differentiate the highlights gives it that "long scale" look which is really not there.

In this case the "hard" data is very misleading, although on a step tablet pt/pd is able to accomodate 9 stops, the reality is that many of those stops are a morass of ugly looking blacks. Although the "data" might suggest the greater ability of pt/pd to fit more tones to the paper the reality is one where many of those are just plain ugly and useless, if anything I would say that azo truly fits the stops printed on the step tablet which are useful.

I am not "defending" pt/pd, but I have to say with all due respect to Dan Smith and Ed Buffaloe, both of whom are persons I respect very much, that I thought this article was a little bit of "fluff". It is impossible to quantify perception by printing step tables and IMO to write an article comparing this mediums is similar to writing an article comparing blondes and brunettes....

 

[avandesande]

I am referring to expanding the scale of the negative. If you look at this article,
http://unblinkingeye.com/Articles/Pyro/pyro.html
you will see that the scale of the highlights are exaggerated by pyro. This compenstes for the smaller scale of the silver paper highlights. The highlight seperation effect of pyro is well documented in the literature. Look at the picture of the lightbulb in Ansel Adam's 'The Negative'

 

[Jorge]

I did read the article, and the effect of highlight separation by pyro although well documented is still a matter of perception. Nobody has proven conlusively that pyro does "better" than any other developer when used appropriately.

If anything again pyro is more effective with pt/pd as it blocks more UV light as explained in the article you mentioned. Arentz and Herbst have done this study where pyro is compared to a "normal" developer and it was concluded that a normal developer is just as capable of producing the same results. As I stated you have to fit the negative to the curve and the pyro stain does not make the paper "better", azo is simply better able to accomodate the separation by its own nature, not because of the pyro negative. IOW if you have a highlight that is 1.87 and another that is 1.9 azo would be able to separate them as shown in the article, but if you have a 1.9 and a 2.0 highlight no matter what you use, pyro, d76 or anything else, the 2.0 would still show as paper white. The fact that the pyro stain can better diferentiate between closer densities does not improve the paper. The paper is only showing what it can do, no more no less, no matter what developer has been used. I would say that the tonal scale of azo is actually relying more on the paper developer used than on the negative. I think Michael has proven this, azo in any other paper developer is just another silver paper, amidol is what lends it the better reproduction qualities.

From my experience in printing in silver I can tell you that given a negative that contains the same reproduction scale of the paper, all the tones will show in the paper. Reproduction is dependant on the paper, not the negative.

This is the problem of doing step tablet tests for something as subjective as photographs. Which reminds me if you go back and look at the azo article you will see that the print reflective density range is exactly the same for both the pyro and the d 76 negatives, this cannot be unless you have some give somewhere, the d 76 neg appears to have better separation in the dark tones. I am sure given a little bit of more work the d 76 negative could have shown better separation in the highlights also.

 

[clay]

Part of the problem with this discussion is that meaningless terms like 'tonal range' and 'tonal scale' are being thrown around as if they had some sort of quantifiable meaning. Jorge is exactly right in his previous posts. The differences between the processes have to do with the reflective density difference between platinum and silver gelatin. Azo/Amidol does not have a greater reflective density difference than any other glossy finish silver gelatin paper. Dmax for all of these range from 1.9-(2.1 in some cases.)

Because of the matte finish that handcoated platinum prints have by necessity, the maximum reflective density is anywhere from 1.3-1.5

(In a *well made* print. As an aside, you will see many basically crappy platinum prints floating around made by some photographers that have some serious technical problems in basic technique. Do not assume you know what a good platinum prints looks like until you have seen one done by a Kerik, a Dick Arentz, a Stan Klimek, or a Stuart Melvin. )

But back to the reflective density thing. If you get a silver gelatin paper with a ^matte^ finish, guess what? The maximum reflective density of a maximum black is about 1.5 - same as platinum/palladium. As Dick Arentz points out by way of Minor White, what really matters is the 'convincing' black. If the paper is delivering a reflective density that appears maximally black to the viewer, he or she won't give a rat's ass whether the Dmax is 1.5 or 1.9. The thing that makes a print 'sing' ,or not, is the gradation between the infinite steps of tone (yes, more than 256, you photoshop users), and how this gradation reflects the actual brightness differences that were present in the original scene.

If you print (with good technique, again) a step wedge on Azo and a step wedge on platinum/palladium, and plot the results, you will notice that the high negative densities on platinum/palladium stretch out into a very long toe. The highlight gradation is very delicate. At the other end of the plotted curve, you will immediately see that the shadow values are also somewhat compressed and have a lower slope (e.g. lower contrast) than the relatively straight line area between ^print^ zones 7 and 4.

The Azo wedge will show an amazingly straight line response, with very little toe and shoulder on the curve. I've done this exercise, and its interesting. Azo/Amidol is strikingly different than Azo/Dektol in its curve shape. The point that Jorge makes is relevant, though: Just because platinum and Azo/Amidol require a density range of 1.4 to completely 'fill up' the print density range just means that you have to have more contrast in the negative to begin with. If you choose to use a process that has a print exposure scale of 1.0 to completely fill up the reflective density range of the print, you can tailor your negative exposure and development to give you just that result.

What does all this mean? I think it means we are technologically capable of producing stunning prints using either process. It just depends on what 'look' you like. Give me the process, and the real life reflective values you want to capture on the final print, and I can make you a negative that will fit the process. It also means that we have the technology at our fingertips to produce trivial, shoddy dreck. Taste, discrimination, and esthetic sensibility will go a heck of lot further than chemistry in producing a fine print. Understanding how the process behaves is only useful if you have a real vision of what you want to achieve.

This whole thing is similar to an argument over "which is better, red wine or white wine?" Believe me, there are some crappy wines of both types, and it seems like it might be more relevant to discuss "which is a better white wine" or "which is a better red wine". And don't ask somebody who hates sweet white wines to give you useful assessment of a bottle of Chateau D'Yquem, or conversely, ask a red wine hater to give you any useful information on bottle of Lafite Rothschild. And my red/white wine analogy is good, I think, in that there are some people who like one or the other, and some lucky souls who can taste and appreciate both.

So drink up and go make some art.

Clay

 

[Aggie]

..

 

[clay]

Kerik does not own a densitometer, and he makes wonderful prints. Don't get something like that just because a propellerhead like me starts talking numbers. The only reason I throw those numbers around is because of a sick fascination with the quantitative that dates back to childhood. They just provide a quantitative shorthand do describe something that your eyes and the meat computer in your head is just about as good at recognizing.

As far as infinite range of tones being a definition of tonal range, no, my point is that any analog process or any paper can give you an infinite range of tones. I think when most people use the phrase tonal range, they mean 'the difference between black and white' . But again, it is an imprecise term, and is being used when there are some accepted unambiguous terms around that describe what I think people are attempting to describe. Density Range [the transmission density difference between the shadow and highlight on a negative), Exposure Scale( the difference in LogD exposure required to make a print from pure white to pure black) are two such terms. They have precise meanings. Tonal range has about as much precision as me telling my spouse that her dress looks 'nice'. BTW, i learned long ago that line is not recommended.

Anyway, what I'm saying is don't get balled up in all the arcana here. Find what you like in a print and learn how to get what you like. The number stuff may help you if you are so inclined, but if you're not, just practice, practice, practice.

 

[SteveGangi]

Hey Aggie, don't worry about it. Lots of us don't have a densitometer. We do have eyes and we do know what we like when we see it (usually). What the guys are saying in a nutshell is that doing something a different way will give you a different look. Sometimes subtle, sometimes not. Look at the work of other people, good and bad. Decide for yourself what it is you like or don't like. Occasionally copy what they do and how they do it, it is a great learning tool. Make mistakes. Some people get all involved with measurements and numbers. They are looking for ways to get a handle on things so they can predict the results and decide how to get there. Many of them are established pros who just can't afford to waste time and materials. They need some way to get consistently excellent results every time, often under horrible conditions, a fixed budget, and within ridiculously short deadlines. Sometimes numbers are just a way to pin down something you already can see, or already "know" but can't quite put your finger on. Do like I do. Let them do all the research, and then take what you want from it. My best advice at least in the beginning, is to keep it simple. Pick a film you like, for whatever reason. Get to know that film, what it can or can't do. Do the same for developers and papers if you are into printing. Once you are comfortable with that, then branch out.

 

[Jorge]

Aggie, the numbers are just to illustrate a point. Actually if anything I am more on your camp after having done all that sensitometric rigamarole. When I first started , like many I wanted to make pictures like Ansel Adams, and I thought a thorough understanding of sensitometry was required. So I did all that, and I learned a lot, but now I am back to developing by inspection, etc. The one advantage of having learned all that was that I know what a good negative should look like, and how to obtain it, but it is not necessary to make great prints. As far as I know Edward Weston never came withing 100 feet of a densitometer.
If you learn sensitometry you have a greater control over your materials, which I think makes expressing your "idea" or vision easier, but by no means it is essential, I think Michael Smith does his contrast developing by the "glug, glug" method...

. he adds more activator to the ABC formula as he thinks is fit, he does not do all the sensitometry.....of course with his experience he has probably made all the mistakes there is to make and knows what to do by intuition.
So dont get bog down on the numbers, is like the coffe cup holder in your car, is nice to have but not essential to the operation of the car.

 

[Jim Chinn]

Aggie,

Using a densitometer is just a more precise way of getting from A to B. There is nothing magical about it. You are basically qauntifying the characteristics of paper and film and how they relate to each other and specific chemistry. As Steve and Clay point out is not required to make beautiful prints. You can get perfectly good info by making tests of film through exposure and developing times in different developers and keeping a notebook of results. A good methodical approach to testing materials will give you just as good a result and allow you to make determinations in the field about how an image will look based on those tests. If you are not testing now, there are several books and sources on the web for materials testing protocols.

The other option is to stick with one film and and developer combination and learn all of its subtleties and characteristics. One photographer who comes to mind in this regard is Ralph Gibson. For years his only film was TriX souped in Rodinal. Yet the range of print characteristics he can produce with this one combination are incredible.

I have borrowed a densitometer a couple of times just to understand how it is used and what it can do for me. I appreciate it as a precision tool that provides certain results, but I just like to do things the hard way sometimes.

 

[David A. Goldfarb]

I've owned a densitometer, and I agree that it's useful to use one for a while, particularly if you are trying to learn from books and don't have access to galleries of fine prints. If you take classes with a teacher who is really competent and can show you what a good negative looks like and how to get a good print visually, that's a perfectly good approach as well. Part of the reason that the Adams books have been so successful, I think, is that objective readings from a densitometer can give you an idea of what you're aiming for, which reproductions from books alone can't really do.