"Long" Tonal Scale Film

Kirk;

The tonal scale of a film is merely the shape of the curve of the response of film to light as a function of exposure density. It is an H&D curve or a plot of Density vs Log exposure.

Contrast is the slope of the curve, and the tone scale is the 'length' of the straight line portion of that curve.

A film with a long straight line portion produces a long or complete, or good tone scale. A large range of differences from light to dark as it were.

Negative films usually have a tone scale with a slope of 0.6 or a rise of 0.6 density units for each one unit of exposure. The d-min (light portion) is usually about 0.1, and the dark portion is usually about 3.0. Reversal films usually have a slope of about 1.7.

Negative paper has a slope of about 2.5 for normal contrast. Since slopes of materials during printing are multiplicative, the slope of the final print is 0.6 x 2.5 = 1.5 which is nominal for a reflection print pleasing to the eye. (notice that it is similar to the slope of a transparency material. Reversal paper has a slope of about 1.0 or slightly less, and the print is about 1.7. That is why reversal prints are slightly more contrasty.

Negative prints are made on the straight line portion of the negative film and therefore have a full tonal range with no compression due to toe or shoulder except that of the negative paper.

Reversal prints are made on the full curve and therefore have compression built in due to the toe and shoulder of the film and paper both and therefore do not look as good. For this reason, making reversal prints of transparencies for magazines or for normal display viewing involve highlight masking and color masking to fix up these problems. If you don't you have prints with severe compression of the scale and a 'dupey' look.

If a negative film has a short straight line portion it is manifested in several ways. It has a short tone scale, it has less overexposure latitude, and it allows the tone compression of the shoulder to show up in the final print giving reduced detail in highlights. This usually arises when a film has low d-max, less than 3.0, or high contrast.

Does this help?

Regards.

Ron Mowrey

Lots of good info in this thread. Thanks people!

Sez Ron. I have no problem with that description, but I don't think there has ever been any agreement on what the term means. In fact, I'd put it more in the category of marketing blather than scientific terminology. I love Anchell & Troop, and have learned a huge amount from the book, but at the same time, it contains many general statements that may be true under specific circumstances, but cannot be considered universal truths. The deeper I get into this stuff, the more I want to see graphs and deal only with carefully defined terms. Those are the only things that can be repeated by multiple workers and inspire some degree of confidence.

Conrad,

The university near me has a copy of the Grant Haist two volume tome Modern Photographic Processing which has many graphs and diagrams, and which explains in detail what tests he performed, how he performed them, what data he generated, and how he interprets the data.

Having read (well, studied might be a better word - it's such a huge work) Haist, and Anchell and Troop, it looks to me as if the Anchell and Troop book pulls largely from Haist's work. You can see this in their footnotes.

What I'm saying is, the gory details that Anchell and Troop left out, are in the Haist books. Henry's book is also interesting, even if I can never remember the name of it. Sigh...

Yup, I'm with Conrad. Kirk, don't forget the more modern term for tonal scale - "tonal range." Just as meaningless, but less dated.

Henry's book is also interesting, even if I can never remember the name of it. Sigh...

Controls in B&W photography....

A paper like Azo has a long tonal scale because the paper's exposure scale can accomodate a negative with a greater density range than normal. Azo can easily print a negative with a density rangeof 1.6 to 1.8, compared to a "normal" enlarging paper this is a great range.

When talking about negatives it is a little bit more confusing, you are correct in thinking that a negative which has the ability to easily change contrast index with development can have both "long" and "short" tonal scales, but then there are films which have inherent "short" tonal range (high contrast) and others that have a long tonal scale (low contrast). Examples are Tech pan and HP5+.

Without getting in long and technical discussions of the films, developers and characteristics, IMO interchanging the terms long tonal scale for low contrast and the opposite, amounts to the same thing.

You think this is bad? Listen to a wine connoiseur. They have the excuse that much of the sensation of a wine would be hard to put in a graph. We use terms that are difficult to graph, like local contrast, and that are sometimes imaginary. That makes me a heretic, but at least I won't go to hell for it...Will I? Please tell me I won't.

Local contrast is a term with two definitions. One type of local contrast is the difference between two points on the curve. The other use is a small area of the scene rendered either on the negative or print, or even the original subject. I still think tonal range wins out for the term that has the most possible non-specific meanings.

Sez Ron, and sez Grant Haist, a very good friend of mine!

I helped him edit his book and we worked together at EK for many years. We also used to work together in my darkroom developing color film and prints, as Grant didn't have a home darkroom.

Please look in the credits section of the book for my name. I believe Grant placed it there. IDK for sure, but then I really didn't care. The friendship of such a great person and great photographer was enough for me!

In any event, it is not hype, it is part of the science necessary to develop a good photographic product. I have coated my own Gold 400 and Ektacolor paper and had fun using them even if they were experimental.

So, I say yes. I'm giving you straight information.

You may believe it or not, as you wish. I was an engineer at EK for 32 years, 15 of them developing products that you have probably used. I hope you still enjoy using them.

Regards.

Ron Mowrey

Ahhh. Sorry, Grant has so many books out there.

To be more specific, I helped with his 2 volume Encyclopedia published by Morgan and Morgan. I edited the Color Photography section for him.

RM

Ron- Cool! Now, who wants the unenviable task of getting everybody on the same page with this term? My experience is that when tonal scale enters a discussion, opinion rules the day. "Long" and "short" don't help me much. Can some numbers and conditions be attached to this thing? Yikes, do I really have to hit the RIT library and start at page 1?

Conrad;

Since we both appear to be in Rochester, just look me up in the phone book and call. I will be happy to sit down with you and draw curves on graph paper to your hearts content. You may have to supply the graph paper. :-D

Since you are at RIT, ask Bruce Kahn about me. Or perhapps Erik at Campus Connections.

Regards.

Ron Mowrey

Looks like subtle facetiousness just doesn't play well in type. And since a real devotee of sarcasm would never use the smiley face :-), it may never work.

Kirk do you really need to fill your head with all that stuff? I like to try out different films/papers etc and see for myself what the finished print looks like. If its to my taste great, if not it goes in the bin, job done. Patrick you won't go to hell, your Vit C developer is wonderfull, this alone will get you a ticket upstairs. Good luck, Norm.

While we're pondering obfuscation, let's not forget the hosannas of Leicaphiles regarding the "local contrast" miracles of Leitz glass.

Rowland, Do you by any chance have the formula for Ektalure? That wonderful paper EK made, didn't market and wondered why it didn't sell, then killed off? You might be able to retire early if you did. ;-) Alexis

Kirk,

I think you are 100% correct. I've never checked myself but have heard that most modern films don't shoulder off. And has anyone checked AZO scale vs. grade 0 or 1 enlarging paper? Seems to me if it reproduces more steps of gray it is just low contrast.

Ron, I'm not actually at RIT. I went there many years ago. When I left, I was determined to move as far away as I could possibly afford. In 30 years, I've made it as far away as Canandaigua!

Lemme get back to the topic and see if I understand this. Say I develop TMX in Xtol 1:3. That seems to work fairly well, but the Dmax is extremely limited, less than 2.0 for the times I like. The film can cover a normal scene, but with little latitude. The straight line is reasonably straight, but when it shoulders, that's it. That's a short tonal scale combination. I can do Tri-X in my PPD/ascorbic acid soup, and get about the same contrast as the TMX. The straight line is straight, but Dmax is up over 2.5. Much more latitude in exposure. So I've got a longer tonal range combo there. I know some of this is built into the film, but IMHO, the developer has a significant role as well. It brings up an interesting question regarding "pulling" film to capture a greater dynamic range in the scene. If you reduce development and thus reduce Dmax, the films ability to capture a wide brightness range may not increase all that much. The midtone contrast will, however, stink. Thoughts?

Aren't we trying to match the film contrast to the paper. Film may go on to high Dmax but it will be hard to print that on normal enlarging paper. When speaking of Dmax's of 2 plus are you talking about using alt process papers? Or overexposing a normal scene so that it's density change falls very high on the film curve.

Thanks for all the responses!

Rowland - Thanks for your discussion of contrast - It does help!

I notice that your discussion consists entirely of examples of color materials. I think this is a significant part of the question/answer. You may notice that I mentioned the use of the term with color materials. And this use is really only time that I think the "long" or "short" tonal scale really makes any kind of sense - and it is only because the processes used for film development (E-6 and C-41) are standardized. But still, and here's my gripe, it seems that the the term "tonal scale" is confusing. Perhaps the use of the phrase "exposure range" makes more sense. It is more intuitive, as it clearly relates it to the type of contrast range in the original subject the film can record.

Rowland, do you agree that for the vast majority of traditional (i.e. consumer) black and white films (not things like the C-41 B&W films), the term long and short tonal scale simply does not make sense, as we can simply adjust the contrast index by changing development times?

Thanks for letting us know your credentials too - it's great that you've been involved in photographic research, and at such a high level. At first I thought you meant your were in the credits for Anchell and Troop, so flipped through it - I didn't find your name in it, but I did happen to see another name in this thread - Stephen Benskin is listed!

Conrad - You said "I don't think there has ever been any agreement on what the term means. In fact, I'd put it more in the category of marketing blather than scientific terminology."

This is exactly the point that I am trying to make. So I was trying to find if there was a consensus, and if not, which uses seemed to be most popular.

Speaking of Anchell and Troop's book, I am actually pretty disappointed with it - I was expecting much more from the book, especially with all the talk and referencing I see on the book.

I too did not get very far into the book before I noticed the lack of development graphs and curves. They say that a picture is worth 1000 words, I think a graph would be worth at least that many when discussing film development. I'm a chemist and I was excited to read so much material about chemical compounds and different combinations, but as a photographer I'm extremely disappointed in them because of the lack of graphs... I understand that they are about to release a second edition, perhaps they will actually plot some of the dozens of film/developer combinations which they seemed to have tried.

Hogarth - I'm a big fan of Richard Henry - I think it is required reading for anyone who really wants to learn the technical side of photography. It's an important work - as much for the info he has in it as well as the skepticism that he had in examining the wide range if subjects that he did. We are all better off for the work he did.

Steven - thanks for chiming in! I agree that "range" makes much more sense than "scale".

Jorge - so when talking about Azo - you are referring to the "exposure range" of the Azo, right? Using ISO designations then, Azo (grade 2?) would be termed a 160 - 180 exposure range. If it is, it falls into Grade 00 for regular graded papers. Which really means that is has a very low "conrast index".

But you say that Tech Pan has an inherent short contrast range. Even though TechPan is not a "normal" consumer film (remember that it started out as a technical/scientific film) you can develop it in HC-110 Dilution A and get a very, very high contrast index. But try POTA or Technidol and you can easily get a CI of 0.50. So you can not really say that any film itself has a long or short tonal range - at least until you specify which developer and development time you are using.

I do think that one MUST get into (perhaps) long and technical discussions of films and developers when using these terms.

Patrick - I appreciate your input - I've long been a fan of your Darkroom Techniques articles. (What is that mag called now? It'll always be Darkroom Techniques to me!)

You MAY be going to hell for such heresy, so I suggest that we work to change the conditions required for admittance - I suggest that only people that use the term "tonal scale" should be admitted!

Stephen - I never use those smilely faces things- see my previous paragraph...

Norman - I DO need to fill my head with all this stuff, and I always try to fill it with more stuff like this in fact.

Trying out films and papers and developers and fixers and stop baths and wash aids and cameras and lenses and filters and ... is sometimes fun, but where does it all really stop? Perhaps with a better understanding of the mechanisms and principles of the stuff that we use as photographers will actually allow us to not only become better photographers, but it will actually free use from trying out a lot of films and papers and developers and fixers and stop baths and wash aids and cameras and lenses and filters and ... only to throw the prints in to the trash!

Lex - I used a Leica IIIf for a while. Perhaps it was just too old to make me excited - or I was too young. Maybe a Leica R would have suited me better. But I have used a Linhof Technika of the same age - now that DID get me excited!

Chuck - see my reply to Jorge in regards to Azo and paper grade.

Conrad - which paper are you using to print your TMAX with a DMax of 2.0? Are you printing on Azo, because that is really pushing the limits on regular papers, graded or VC. A DMax of 2.5 is even higher (!) and should actually be even harder to print. You should have a "shorter" tonal range, as you have a higher contrast range which means a smaller "Exposure Range".

Thanks again to every one - I hope to hear more thoughts.

Kirk

Chuck, I'm not doing alt process, and I don't want to print on grade 00 paper, but I'm not convinced that adjusting development to match the scene to the paper is always the way to go. IMHO, sometimes it's better to maintain the midtone contrast, dodge and burn to get everything else where it has to be. I want some headroom so I can place the shadows at a suitable place on the toe, and not have to worry that the highlights will get squashed flat. What I suspect, though am not absolutely sure about, is that reducing development lowers the contrast, but may not greatly extend the exposure range of the film. I.e., if the highlights were compressed with normal development, they'll be compressed with reduced development. Which goes back to the tonal range topic. You need long tonal range materials for long tonal range subjects, and just reducing development and contrast doesn't turn short range materials into long range materials. Sometimes I barely make sense to myself- does that make sense to anybody else?

just reducing development and contrast doesn't turn short range materials into long range materials

Sorry Conrad, I have to disagree with you here. I do agree with you about changes to local contrast.

The term tonal scale or tonal range is just too nonspecific. It's like saying "gutsy development." IMO, the term is used most often because there wasn't any quantitative testing.

If we are talking about films, isn't contrast index, density range, or log-H range more informative and specific. "The film has a long tonal range" doesn't mean as much as saying "at a CI 0.60, there are no signs of the film shouldering off within a scene's average log-H range."

When discussing papers, why not use reflection density range, or log exposure range? I just think the tonal scale / range term is so ubiquitous that most people don't stop and think how weak a term it really is.

To me, exposure range and tonal scale are not the same. Exposure range implies the length of the straight line portion of the H&D curve, and tonal scale implies the overall shape and contrast of that curve.

Everything said about color is applicable to B&W. The only reason color materials generally cannot yield varying contrast with good results by changing development times (other than push results) is because you must match 3 or more color layers with the same exact curve shapes at all conditions you select.

I could append hand drawn curves here, but generally speaking, in descriptive terms, any curve can yield a good photograph as long as the negative film has a long straight line portion, as long as the photographic exposure is exactly on that portion, and as long as the print material matches the film to yield a satisfactory print within limitations of reflection materials.

For an example, any combination of y x z = 1.5 where y = film mid scale contrast, and z = paper average contrast will give the result you want. The limit comes in due to compression of detail in the toe and shoulder of the film and of the paper. All imaging systems have a toe and shoulder. In electronic imaging it is termed V log E (Voltage Log E) instead of D log E. (Density log E). Your film may have a long straight line curve with no shoulder, but way out there somewhere, the shoulder rolls over and flattens out. That is a fact of science and is determined by the way the silver has developed, and the silver lay down (or silver spread).

Developers give different results in B&W, in terms of the way the silver metal is laid down. It can be as filaments, tablets, coils, rods, etc.... I have seen 100 mg/dm^2 of silver be anywhere from non-visible to a density of 3.0 based on the form laid down in development. This also impacts sharpness and grain. Darker silver images have more contrast than finer lighter deposits of silver. They give higher contrast, usually. Therefore, a B&W developer does not necessarily produce a higher contrast in silver metal, but only in the density of that metal. It may produce more metal.

For this reason, a photographic engineer has to rely on actual chemical silver analysis to determine the amount of silver developed and compare it to density.

Developers in color determine rate of dye formaton in 3 layers, and final dye stability. The form of the silver is not important except as a measure of where the dye deposit forms for sharpness and grain. Paraphenylene diamine developers are usually fine grain and sharp by their very nature. A plot of anylized silver vs dye density yields a value called 'dye yield', the slope of which is the 'equivalency' of the coupler in a given process.

MQ developers vary in their ability to produce silver density much more than paraphenylene diamine developers. Silver analysis vs density is the measure of efficiency of B&W materials.

The toe region and shoulder region of an emulsion is due to several factors. All grains are not equally sensitive to light. All grains are not the same size. All grains do not develop, and if they do, they do not develop at the same rate. This causes a toe and shoulder. Analogs exist in digital 'electronic' photography.

In the toe region, we find coarser grains which are more light sensitive. The very start of the toe, the inflection point, is called the threshold speed. It is several stops faster than the ISO speed of that film and represents the maximum speed available for that film with push. Basically, you are trying to turn the low contrast toe into a 'normal' contrast straight line, but in doing so, you jack the mid scale curve up sky high thus destroying detail in light areas. If the exposure goes beyond the threshold speed, then everything is uniformly white in the negative and black in the print. No shadow detail.

In a pull process, you are trying to pull a straight line out of the shoulder region of the film. This often works less effectively than a push.

All along, you have to keep in mind that this film may be a blend of 3 or more emulsions to get this long straight line curve. As you vary development, you may introduce kinks and bends as these emulsions respond differently to changes in developer or time or temperature. This goes for B&W and color.

So, did this add more to your understanding?

BTW. I have no formulas. I'm already retired. I do remember several formulas, but not in the detail to recreate them, not that I'm really tempted to do that. I would rather use the knowledge I have in a general manner for the education of other photographers, as I'm trying to do here. If any of you want an example of a real emulsion and coating formula that works, go to Jim Browning's web site and take a look. He makes very beautiful dye transfers using his own home-made Matrix Film.

Google Jim Browning for the URL. I don't have it handy. Also Google Grant Haist for a list of all of his books. He was a prolific writer and a great photographer for National Geographic, having supplied them with several feature articles.

For those that don't know it, Grant suffered a severe stroke two years ago about this time. Last summer, he was still under care during his recovery, but does not recognize many of his friends. He is probably on his way up to Rochester from his winter home in Fla. if he still follows his old schedule. I may try to contact him, but as of last fall, he did not remember who I was.

His last two photographic safaris were to the Falkland Islands, and to the Grand Tetons. During the trip to the Falklands, he was bitten by a penguin and fell down some rocks. The only things damaged were his glove, his ego, and his camera. He was here right after that trip going through my spare parts box for a screw for his Nikon to fix some of the damage. Those are the last pictures I have of Grant.

Just before his stroke he told me he had frozen the Grand Teton 4x5s in his freezer, as he didn't have an opportunity to process them. For all I know, they are still there. Maybe someone can update me.

Regards.

Ron Mowrey

To me, exposure range and tonal scale are not the same. Exposure range implies the length of the straight line portion of the H&D curve, and tonal scale implies the overall shape and contrast of that curve.

Fine, but most sources don't seem to define it. To me, they are the same. Jones used to use the term scale for everything, brightness scale, exposure scale, etc. I've seen scale used in papers up through the 50s. Now it's luminance range, exposure range, etc.

Kirk's question was not really what a particular person thinks it means, but how it is used in so many different ways in literature. Scale or range, I've seen tonal scale / range used to refer to both the exposure range of a material and the density range of a material, and those are two different things in any bodies' book.

Jorge - so when talking about Azo - you are referring to the "exposure range" of the Azo, right? Using ISO designations then, Azo (grade 2?) would be termed a 160 - 180 exposure range. If it is, it falls into Grade 00 for regular graded papers. Which really means that is has a very low "conrast index".

As I understand it you got it.

OT; AZO came out in 1898; by Rochester's Photo Materials Co. Kodak then bought out Photo Materials Co; since the market for this cool product was good..

I think that there is a point here that we are all missing.

Interal to EK, Fuji, Agfa, etc. there is a consistant scientific terminology that is also used in the SPSE journals and elsewhere. There are/were also trade publications such as Popular Phtography, Modern Photgraphy, Darkroom Techniques, Photo Techniques, etc. In the trade publications, the terminology is much looser than it is in the scientific circles. And there is much more urban myth in the general photographic materials using public than is appreciated.

I didn't realize this until I started reading things here on photo.net and then I saw a lot of things said that just were not correct or were distortions of the truth. Things like 'you can't do color at home satisfactorily', and 'color chemicals cause cancer' and 'Kodak cross packages bad professional film as consumer film'. Those are just a few of the comments that surprised me.

As I ponted out in another thread, pyro developers are more likely to cause health problems than most color processes. (Cf the current issue of Photo Techniques) So, statements like I have cited in the previous paragraph above are common here but they are not correct.

If I had to describe a films characteristics, I would describe a film precisely in this manner. Here is the sensitometric (H&D) curve using exactly this exposure, of this film in X developer. Here is the curve in Y developer. They compare in the following manner in the toe, mid range, and shoulder.... etc. Here is the silver analyses of the two curves. Please compare the silver vs density curves to see the effects of developer X and Y on silver development as it pertains to percieved latitude as seen by etc. etc. This general example shows how I might describe something. I would supplement it with graphs and data.

I have had to do this when I submitted data for patent purposes or publication or delivery at a talk on photographic subjects. Words are very difficult to use to express photographic data, and it is hard to get that data. Very few of us are equipped to back up a curve with silver analyses. Indeed, very few of us can produce a curve.

Therefore, we must make do with the long verbal descriptions going on here to come up with a consensus that does not include any outre statements such as the really left field, but real, quotes that I included above.

As a result, we have all gained a better understanding of the technical side of photography, and nothing unusual or way out was said or claimed. I think that this thread did a good job helping us all.

I have never had to describe photographic characteristics in words alone. It was a first for me too. I always had curves and detailed analyses to back me up.

I would like to hand draw some curves sometime and use them to supplement one of these discussions, but it is very tedious, and since they would be hand drawn, what 'reality' would I have to back them up. It would just be hand waving. It might help understanding though. So, perhaps I might someday do it.

Regards.

Ron Mowrey

This, and some other recent threads, make me think membership in photo.net is one of the great bargains of the century! I've just spent some time looking at film curves in my old Kodak data books. Many of the films are no longer, but it was the quickest way to see lots of curves for different development times, all in one place. Also re-read the old P-315, Scientific Imaging with Kodak Films and Plates. Wealth of good info on processing in there. Two conclusions. 1) The 4-quadrant tone reproduction graphs send a huge amount of fuzzy terminology, opinions, and questions, to the scrap heap. 2) As far as I can tell, based on the fact that almost no published film curve really extends out to the shoulder, and sufficient density is still available for any paper, pictorial images just don't get up that far. Almost any decent negative will use part of the toe and the straight line only. Possibly my TMX in Xtol 1:3 is a bit unusual in its early shoulder, but even that is sufficient to the task.

Ron, curious what you think of PPD developers. We can start another thread if you like. They aren't popular for b&w work, and everything I've read suggests a serious lack of acutance. An early formula I tried was awful, but my current version is pretty good. The very fine grain is well suited to scanning.

Here I have Kodak databooks going back prior to WW2; the SPIE handbook; gobs of Optical books; etc. Old Super-XX had a long straight slope; with little shoulder falloff. Plus-X pan Professional had a long straight slope; with little highlight shoulder droop to . These films were good for capturing long tonal scales; with excellent highlight separation.

It was commented above that some scenes encompass a 1.6 to 1.8 density range. That would be about 3.0 Log E with a normal negative film. None of that exposure should be on the toe if you wish to avoid image compression, and none should be on the shoulder for the same reason. Therefore, this defines the straight line portion of the curve of a given film / developer combination. A standard 21 step tablet of 0.15 log E will capture 3.15 log E, and a 0.3 tablet will capture 6.3 log E.

A typical good negative film can capture 1.8 log E on the straight line portion, and still have at least one stop on either side, minimum, for exposure error.

If you think you can capture the full range of densities in a scene by using the toe and/or shoulder of a film, you are misleading yourself. You can get good images, but not as good as with the straight line portion. OTOH, all reversal films, properly exposed, use toe and shoulder. You have to have white and dark in the transparency.

In the negative you do not. You only need it in the print. The print material has the only toe and shoulder you should use. This is why you can live with some fog in a negative but not in a print material or a transparency material. In a transparency material, 'fog' brings down D-max, and 'stain' brings up D-min. They use these two terms there.

Some negative materials do not seem to have a shoulder. That is because the exposure was not broad enough to show it. The film has latitude broader than the step tablet used to expose it, or the film was underexposed to the tablet resulting in the D-max being off the right side of the graph. This is not uncommon with good negative films BTW. A typical reflection print is about 2.0 log E. You cannot go much broader than that due to D-min on one side and the reflection limit imposed at about 2.0 density on the other side due to multiple internal reflections.

As far as PPD developers, I believe that they tend to give fine filamentary silver deposits which are low in contrast. Depending on formulation, they can give good or poor sharpness. IIRC usually, a high solvent developer is better in this case, but that is not always true.

If you guys want more information, try Mees or Mees and James "The Theory of the Phtographic Process". Eaton's book "Photographic Chemistry" is also good.

I have just about every databook and dataguide published by EK since 1952. I have formula books back to the 40s. This includes formulas for reversal B&W processing, Matrix film processing (tanning), Chromatone, Bromoil, and Dufaycolor. One of the most interesting books describes how to expose Super XX film (tricolor) and develop in a Kodachrome type process to get color transparencies by laminating the 3 negatives together.

Ron Mowrey

"And has anyone checked AZO scale vs. grade 0 or 1 enlarging paper?"

A negative that prints easily on the Grade 2 Azo that they're selling now (Kodak keeps changing it) developed in amidol will yield a roughly equivalent print on Bergger VCNB paper with 30-55 units of yellow dialled in developed in Dektol 1:1. (Contrast grade of 1/2-1.) If a water bath is necessary for the Azo print, you'll probably end up dialling in 80 units of yellow, which is a contrast of about 0.

Kirk, I enjoy doing it my way, by trial and error, and yes I appreciate that knowledge is the key, but I would rather be taking photographs and making prints, than spending endless hours with my head in technical books. I am happy with the amount of trash I produce, we all have our standards yours are probably a lot higher than mine. Do you enjoy your research more than taking pictures? Each and everyone to his own, best wishes, Norm

Conrad - I think I understand what you are saying! I've often used the same printing technique that you mention - extend development and then dodge and burn the image back in. I think that I find this looks good sometimes as you get better tonal separation in the middle tones, and you can usually burn the highlights and dodge the deepest shadows back to where they are not too white or too black. It gives the middle grays more contrast when you do this - it looks somewhat more like a print that has had a contrast mask as you get a more contrasty looking print without having to do the masking. Of course, there are none of the edge-effects that unsharp masking gives though.

But you must have something wierd going on with your density measurements if you have a printable Dmax of 2.0 on regular photo paper. How are you measuring them?

Kirk

Kirk, Conrad;

Looking at some film curves, a density of 2.0 would be just about right for a good exposure on film. Looking at 2.0 on paper, it would be just at the rollover point of the D-max, and would position an exposure properly. On glossy surface a D-max of 2.0 to 2.4 or so is average, on matte surface the D-max is usually lower.

So, whether you are talking about paper or film, 2.0 is a 'good' D-max. It is a good aim point for the maximum density in either film or paper measurements. That is, if contrast is normal.

BTW, have any of you dodged with VC filters on VC paper? This can give you some very nice results. Or with color filters on color paper? Another way to get interesting effects.

Ron Mowrey

Rowland - Thanks again for the long replies - I appreciate the time and effort!

I'm afraid that I'm a bit lost in your discussion of the mass of silver/unit area - I think you are trying to point out that the density of a negative can vary greatly despite the actual silver content in the negative. But that seems to be a bit of a tangent to the subject at hand here. Please correct me if I am wrong.

A few things you did say did really catch my eye - you said, "To me, exposure range and tonal scale are not the same. Exposure range implies the length of the straight line portion of the H&D curve, and tonal scale implies the overall shape and contrast of that curve."

I guess my entire question really circles around one word that you use - "implies". So do each of these phrases only "imply" something, or do they really have specific meanings. This is my whole issue with this subject. As Steven say, most people do not seem to define these terms.

You said, "any curve can yield a good photograph as long as the negative film has a long straight line portion, as long as the photographic exposure is exactly on that portion, and as long as the print material matches the film to yield a satisfactory print within limitations of reflection materials."

That pretty much sums up my entire hypothesis - that any film can reproduce all tones in an average scene and thereby give a good photograph. We should not be confusing everyone by using terms like long or short tonal range. Perhaps we should really be discussing properties like graininess, sharpness, acutance, or speed.

I thoroughly agree with you that all photgraphic (digital on film) materials have a maximum linear exposure range, with a shoulder that rolls off our response as we approach that maximum. I guess I am trying to point out that for the vast majority of films, the linear range is more than sufficiently long that we can satisfactorily reproduce the images that we are taking, given that we do match our film and development to the grade of the paper.

Anchell and Troop do mention films with 2 emulsions - they mention that Ektapan has two emulsions, saying "it has a complex double coating of two emulsions with different speeds and different contrast." Which films are using multi-layered emulsion? I have noticed that with TMax 100 in XTOL 1:3, I get a decrease in slope around Zone V or VI, I take it this could be a result of the film having more than one emulsion?

I'm sorry to hear about Mr. Haist and his stroke. That's really too bad...

If you have some diagrams, even if hand-drawn that you think would help in discussions, please do post them. I'm sure other would find them helpful too.

Kirk

Rowland - I think you heat the nail on the head here, " In the trade publications, the terminology is much looser than it is in the scientific circles."

What is the definition for "tonal range" that is consistently used in scientific journals?

And you said, "And there is much more urban myth in the general photographic materials using public than is appreciated."

I am all for myth-busting - urban or not! I agree with you that a lot of crap get flung around in trade publications, but it is no-where as bad as what gets flung around on the Internet. It reminds me of something that Oscar Wilde believed to have once said, "An expert is an ordinary man away from home giving advice". Well, thanks to the Internet, Wilde's ordinary man can now remain at home and still be an expert! (And since he is one of my favorite authours, I also have to toss in Arthur C. Clarke's comment, "For every expert, there is an equal and opposite expert.")

I appreciate your efforts here to try and bring a better understanding to the subject!

Kirk

Ron - I guess I'll address you this way as you seem to sign your posts this way -

DMax - I agree that 2.0 or so is a good DMax for paper, and probably for films, but since we are trying to match our papers to films, some people more closely than others, 2.0 and above is way above what most papers can handle as far as dodging and burning goes. As I mentioned above, grade 00 is defined as ISO range 160 - 180 (density range of 1.6 to 1.8). As Conrad mentioned that he was not printing on really soft paper, I wonder how he is measuring his density range. Perhaps he is actually measuring DMax of the film, but that he is actually using a much lower maximum image density in his negatives.

I have dodged and burned with different VC settings - it works really well! It is the main reason that I do not use graded papers. I like the flexiblity that the VC papers give. I do not practice split-filter printing, but I only change the filter to burn in a particular area after an overall exposure has been given at a filter setting that fairly matched the density range of my negative.

I have not used colored filters on color prints, as I typically print color to match my 4x5 transparencies. I have seen Christopher Burkett printing in his studio, and he was removing the blue tint that flared into the top of an image by printing the top of the transparency through a yellow filter. He was printing his famous photo of aspen trunks. Quite interesting! You can see his work at http://www.christopherburkett.com/ He is a master at Cibachrome.

Kirk

Kirk;

You have given me a lot to respond to. I'll try to do it justice. I'm going to be away for about a week, so I'm busy doing 1000 things at once.

I mentioned the silver quantity vs density to point out how one B&W film can often give quite different results in different developers. High contrast in one and low in another can come from either a different quantity of silver deposited, or a different form of silver deposited. And, if a film consists of more than one emulsion, there may be bumps in the curve or changes in contrast in mid scale depending on the developer used. So, I believe that my comments are not necessarily tangential to the main topic. Espeically since many films are blends of several emulsions whether it is commonly known or not. It would take and electron micrograph of the film to tell unless the emulsions were coated in different layers. Even then it might be difficult to tell.

Exposure range and tone scale are merely imprecise to me. I prefer being more specific in my description. I would use the example I gave above, being explicit in toe shape, shoulder, lenght of curve and slope. I would describe it by showing examples. In other words, to describe a given film or paper, words alone do not suffice, particularly imprecise or vague descriptive words. A long tone scale tells me nothing. A film with a gamma of 0.63 and a straight line portion of the H&D curve of 1.75 log e tells me a lot more. Then comparing it to a film of 0.71 gamma and a straight line of 1.55 log E tells me that the second film has a shorter tone scale and a higher contrast, but it is told to me quantitatively. I even know the approximate gamma of paper to use to get nearly identical results in a print made from each of those films.

If both had a gamma of 0.63 and one had a straight line of 1.75 and the other 1.55, then I would wonder where the loss was and I would need information on the toe and shoulder. You see, that tells me how much under and over exposure latitude those two films have. Otherwise, the data are incomplete.

In many photographic journals and publications, the manufacturers reps and scientists try to keep to main stream terminology, but back up statements with curves. You will often see that in EK publications. Sometimes, vague terminology is used to avoid being pinned down to a given curve or description because it would either give information away or would perhaps pin the company down to a specification when it was not their intent do do so.

To state my feeling another way though about exposure range and tone scale, think of range as a value or number stating the number of useful stops in a film that lies on the straight line portion - the range of stops. The tone scale implies all of the curve, toe, shoulder, and slope, and implies how the 'tone' of the original is captured. Is it high or low in contrast, do you have enough latitude for this scene, will some of it be captured outside the straight line of the curve, etc....

As for ISO, it is also related to the speed of a given film or paper, as you are aware, therefore ISO used with paper may imply a given tonal range, but two iso 160 papers print with the same exposure. I have gotten different tonal ranges from papers with the same ISO. An ISO 200 paper will have a different on-easel speed. It may have the same tonal range as a slower or faster paper. IDK for sure, as I am not up to speed on this, but paper speeds are often measured differently than film speeds.

Since I quit working on papers before ISO came into use, I cannot say for sure, but I know that I have had two papers of the same or very similar tonal ranges with different speeds and different ISO ratings.

As for experts. A wise man once said that the word expert is made up of two parts "an EX is a has been" and "a SPURT is a drip under pressure". Clarke also said "sufficiently advanced science seems to be magic" or something like that.... I sometimes wonder how that applies to photography. It seems like making film is 'magic'.

Regards.

Ron Mowrey

Ron, I believe Kirk was talking about ISO R (range and there's that word again) and not ISO paper speed.

According to the 3rd edition of The Focal Encyclopedia of Photography, there isn't an entry for "Tonal Scale" or "Tonal Range." The closest term they have is "Tonality" which was written by Stroebel. He defines it as, "The overall appearance of the densities of the component areas of a photograph or other image with respect to the effectiveness of the values in representing the subject." This sounds like Ron's definition of tonal scale.

Photographic Materials and Processes uses tonal range in the index, but doesn't use the term in the text. Let's just call these terms what they are, two very general popular photographic terms that have no specific meaning and are essentially meaningless. It's time to pass a law and have the terminology police issue a fine whenever used. All funds generated can go to the upkeep of Photo.net.

Steve;

You can see that I'm out of touch with some of the 'recent' definitions or usage in B&W paper technology. As to the rest of it, amen.

Imprecision and vagueness reign! I just don't know what most magazine articles or other hype mean nowdays. Ah well.

Regards to all. This is an interesting thread.

Ron Mowrey

Just for the record, I was talking about a Dmax of 2.0. Nothing in a typical scene (mine anyway) would get up that far. Ron, you said something that surprised me, that ideally everything should be on the straight line portion of the curve. That goes contrary to everything I've see published, including various notes from EK. OTOH, I'm just in the middle of some prints where I wish the shadow separation was better. It's good by most standards, but the images would be much stronger if it were better. I don't have a spot meter, nor a way to measure small areas of a 35mm frame, but I'm sure the shadows are on the toe. Lots of detail, but not enough contrast. I bracketed, so my next experiment will be to print what I would normally consider too dense a neg, and see if the situation improves, and what the penalty is. Have a good trip!

This is among the very few threads that is so informative it bears being made more accessible for future reference. But being a discussion forum rather than a website structured like a magazine or journal (for example, Ed Buffaloe's unblinkingeye.com site), it's difficult to find a way to make particularly good discussions readily available. A search engine isn't very helpful in such cases.

For some time there's been some discussion about developing an FAQ specifically for the b&w photography forums. This would help address those routine questions, usually from beginners.

However I also believe there should be something like an RAQ - Rarely Asked Questions (lame, I know, but it's the best I can come up with right now). The RAQ would include threads such as this one, generally more technical in nature, separating mythology from fact and helping to clarify the science of photography for those who are interested. (I must admit, I'm only moderately interested but I respect those who are fascinated by such discussions).

Unfortunately I have no way to reformat the way the photo.net forums are set up. I can't create an FAQ section or anything like that. So for now I'm going to, on rare occasions, add particularly informative discussions to the "About" section, which can be clicked on toward the top of each forum home page. This section is generally used only to make a brief statement regarding the purpose and rules of the forum, as well as to list the moderator(s).

I'll update this list occasionally, but only for discussions that impress me as particularly juicy. If I happen to overlook a good candidate for this list I'm open to suggestion and can be reached by e-mail.

Ron - You said, "Exposure range and tone scale are merely imprecise to me. I prefer being more specific in my description. I would use the example I gave above, being explicit in toe shape, shoulder, lenght of curve and slope. I would describe it by showing examples. In other words, to describe a given film or paper, words alone do not suffice, particularly imprecise or vague descriptive words. A long tone scale tells me nothing."

So it seems that we DO both agree - As you say "a long tone scale tells me nothing". That is what my entire point has been. I really do wish that magazines and even regular people were willing to take the time and learn enough about the materials they are using to actually be able to give much more precise descriptions. It could clear up a LOT of poor and outright bad information that is given out in magazines and the Internet - Photo.net included.

And just for clarification - Steven was right - I was discussing ISO contrast ranges when talking about paper grades, not the speed of the paper.

Your right about Clarke's quote - that's his Third Law: "Any sufficiently advanced technology is indistinguishable from magic." And the more urban legends I run across while learning about photography, the more I start to think that perhaps the perception of photography, even among the majority of photographers, is magic.

Kirk

Conrad - thanks for clearing this up about the Dmax. You should look into getting a spot meter. I use a Pentax Spotmeter V - nothing fancy, but it works. Even if you are using 35 mm gear, you will find that it can help you keep the shadows from getting to far down the scale. Also - go ahead and give a bit more exposure, from your description of your printing style, you should do fine, since you like to print down the highlights into the print.