18 stop Subject Brightness Range on Tmax400

[Steve Gledhill]

As part of my periodic checking of my processes I carry out a test which displays the resulting integration of all of my processes. The attached PDF shows the output and confirms just how amazing a hybrid workflow of film and scanning can be. Some of what I choose to photograph has exceptionally wide subject brightness range in which ideally I want to capture detail from the deepest shadows through to the brightest highlights. Typical of such subjects are the insides of churches or cathedrals with the deep shadows under the pews and the brightest highlights in the sunny windows.

The linked PDF below shows that I can get 18 stops of SBR onto my film and scan the whole range such that all of it is useable. I would agree that the separation at each end of the range is limited – but even for my subject matter, 18 stops is almost always more than I need. It is possible that an even higher range at the highlight end can be accommodated but I haven’t tried.

I’m providing this information for general interest. I’m not making any point here other than to demonstrate the incredible range capability of film which is then available through a digital workflow. Perhaps everyone is already aware of this?


Link to 18 stop PDF (http://www.virtuallygrey.co.uk/files/9311/18stopwedge400tmaxsjg01.pdf)
If anyone is interested in my workflow which gives rise to my being able to have 18 stops of SBR available to me, it is nothing special or difficult, indeed it is very straightforward:


Tmax400 5x4 film rated at ISO400 processed in XTOL (1+2) in a Jobo with continuous agitation at 24°C for 9 minutes. Scanned in an Epson V700 using Vuescan.
If anyone interested in how I make the step wedge (linked above):


This does take careful planning. I photograph a light coloured painted wall in shade. As chance would have it a meter reading for Zone V is ½ second at f64 which falls nicely in the middle of the exposure range that I will be using. I use a standard film holder to the darkslide of which I attach with clear tape an 18 step ruler which allows me move in the darkslide one step at a time. You need to experiment with the empty holder to ensure the 18 step ruler is positioned correctly. I start with the slide almost fully out, except for the first strip which is my “Unexposed” strip in the attached PDF. The first real exposure I make is 1/250 sec at f64 which equates to Zone -2. I then move the dark slide in to the next strip position and make the second exposure which needs to be the same as the first which cumulatively means that strip (indeed all of the rest of the sheet) will have received 1/250 sec at f64 twice – making 1/125 at f64. This gives my Zone -1. Move the darkslide in another strip and this time expose for 1/125 sec at f64. This means this strip and the rest of the sheet will have had a total of 1/60 sec at f64 for Zone 0. I repeat this all the way through to the end. This gives me 18 strips, 1 unexposed and 17 exposed.
All of this does suggest a few interesting consequences – such as in a hybrid workflow, how should I rate my film. The above shows that if I place my deepest shadow detail on Zone 3 then there are actually 6 further stops below that recordable on the film! So perhaps for general use I could rate my Tmax400 at say ISO 800 or 1600 or even 3200 and still have plenty of shadow detail to play with. The additional speed could come in handy sometimes.

I did wonder which forum group to enter this into as its really a hybrid workflow. I plumped for Digital.

[darr]

Thanks Steve!! Your work is beautiful to say the least. :)

Kind regards,
Darr

[Bruce Watson]

I read years ago that TMX had a range of at least 22 stops in the lab. This was before widespread use of scanning, so it was beyond any printing technique of the day to make use of this huge amount of data. It was just a laboratory exercise.

I'm curious however about how to measure what film actually does. The thing about film and developers is that slope of the response curve. I can manipulate that slope at will using the normal tools of developer, dilution, temperature, and time. Such that an SBR of 18 stops can be crammed into a density range on film of maybe 1.5 (I have no idea what your Dmax actually is, so I'm just using 1.5 as an example).

The question is, did I actually preserve the full separation between the stops of SBR? Or, how much separation in density do I need between the stops of SBR to record it correctly? Does it have to be a log density of 0.3? Is 0.1 enough? IDK. I never purposefully pursued answers to these questions as I don't seem to be attracted to subjects of such high SBR.

OTOH, I have done some experiments in trying to optimize my film, exposure, and development for (drum) scanning. What I found is that reduced Dmax was better for scanning. To a point. As I reduced Dmax I got to a point there I was squeezing tonal detail too much and wasn't able to fully replicate it in scanning. IOW you can shoe horn too much SBR into a restricted density range and lose some of it in the process.

Then came the printing. The restricted range of light reflecting off a paper print is the limiting factor in all this. And that depends mightily on the amount of light available to reflect off the print.

Where I'm going with this ramble is that really large SBRs get compressed mightily in the final print. In part because of the limited dynamic range of the print -- the laws of physics are the laws of physics and all that. But mostly because we want a decent looking print, which means mid-tone contrast. Which in turn means compression of the shadows and the highlights -- or clipping of some of the shadows and/or highlights. So even though we can record and process so that we preserve all the SBR of the scene on the negative, we can't necessarily show it all on the print. Or even want to show it all on the print.

But that would be where light boxes and display transparencies come in I suppose. :D

Still, good work. TMY-2 is my only B&W film these days. And this is partly why.

[Steve Gledhill]

Thank you Darr.

[Steve Gledhill]

I read years ago that TMX had a range of at least 22 stops in the lab. This was before widespread use of scanning, so it was beyond any printing technique of the day to make use of this huge amount of data. It was just a laboratory exercise.

I'm curious however about how to measure what film actually does. The thing about film and developers is that slope of the response curve. I can manipulate that slope at will using the normal tools of developer, dilution, temperature, and time. Such that an SBR of 18 stops can be crammed into a density range on film of maybe 1.5 (I have no idea what your Dmax actually is, so I'm just using 1.5 as an example).

The question is, did I actually preserve the full separation between the stops of SBR? Or, how much separation in density do I need between the stops of SBR to record it correctly? Does it have to be a log density of 0.3? Is 0.1 enough? IDK. I never purposefully pursued answers to these questions as I don't seem to be attracted to subjects of such high SBR.

OTOH, I have done some experiments in trying to optimize my film, exposure, and development for (drum) scanning. What I found is that reduced Dmax was better for scanning. To a point. As I reduced Dmax I got to a point there I was squeezing tonal detail too much and wasn't able to fully replicate it in scanning. IOW you can shoe horn too much SBR into a restricted density range and lose some of it in the process.

Then came the printing. The restricted range of light reflecting off a paper print is the limiting factor in all this. And that depends mightily on the amount of light available to reflect off the print.

Where I'm going with this ramble is that really large SBRs get compressed mightily in the final print. In part because of the limited dynamic range of the print -- the laws of physics are the laws of physics and all that. But mostly because we want a decent looking print, which means mid-tone contrast. Which in turn means compression of the shadows and the highlights -- or clipping of some of the shadows and/or highlights. So even though we can record and process so that we preserve all the SBR of the scene on the negative, we can't necessarily show it all on the print. Or even want to show it all on the print.

But that would be where light boxes and display transparencies come in I suppose. :D

Still, good work. TMY-2 is my only B&W film these days. And this is partly why.

Interesting Bruce. I suspected more that 18 is possible - but who needs it? And it is certainly true that as you squeeze more in you have less separation between tones to work with. Although I have a strong science/maths background I'm not actually interested directly in the numbers. For me it's does it look right, can I work with it, can I improve it. The one thing that is I believe implied by your response though is that all of the image gets compressed for the final print. But that's certainly not always the case. In a lot of my work I do a great deal of selective or local contrast work where I stretch the contrast in the shadows for example. Same for the highlights, and for the mid tones for that matter! This of course gets into the whole business of how well one does selections in Photoshop so as not to make the boundaries of the manipulations obvious. Having all the detail in the negative makes that all possible.

[BetterSense]

Interesting. When I think of high SBRs, I think of overexposing and then underdeveloping the film. I was surprised that you were shooting the film at 400, but then you are saying that you can retrieve information below zone 5 to such an extent that 400 is actually conservative. I also wonder what the contrast is doing at these extreme edges, I wonder what your dmax is, and I wonder how all this relates to making projection silver prints.

[Rick Olson]

I shoot TMY for a great deal of my medium format and large format work (5 x 7 to 8 x 20) and I am constantly amazed at what this film can do. I also expose it at 400 and have never had any problem securing the necessary shadow and highlight detail. If I was given one choice of film to shoot for the rest of my days, TMY would be it without question!

Rick

[sanking]

Interesting Bruce. I suspected more that 18 is possible - but who needs it? And it is certainly true that as you squeeze more in you have less separation between tones to work with. Although I have a strong science/maths background I'm not actually interested directly in the numbers. For me it's does it look right, can I work with it, can I improve it. The one thing that is I believe implied by your response though is that all of the image gets compressed for the final print. But that's certainly not always the case. In a lot of my work I do a great deal of selective or local contrast work where I stretch the contrast in the shadows for example. Same for the highlights, and for the mid tones for that matter! This of course gets into the whole business of how well one does selections in Photoshop so as not to make the boundaries of the manipulations obvious. Having all the detail in the negative makes that all possible.

You work is very nice, and thanks for sharing, but Bruce is right in that capturing a longer range is possible. Whether you need or want it is another matter. The procedure I use in exposing B&W film in scenes of very contrast is simple , just meter for the deepest shadows where you want detail and develop in a two-bath formula that automatically limits highlight contrast. Regardless of how much the scene is compressed one can scan and manipulate the image file in Photoshop with curves and other controls to increase local contrast at any point on the curve.

My point is not to suggest that other methods are better than yours, only that there are several strategies that can be used to capture scenes of very great contrast, and assuming one is scanning and then working the file I think all of them can be efffective.

Sandy King

[ic-racer]

Hard to tell from that without seeing the densities plotted out in the standard H&D curve, but in 1986, when I first tested T-max 400 I got about 14 stops of usable curve. So, I'm not sure if this represents any new information. Both my sensitometers I currently use have only 21 step wedges so I have not made a complete curve for "new" T-max.

You mention placing the deepest shadow on zone III which puts the main image onto the straight line. I have been doing that since T-max first came out in the 80s.

[Kirk Gittings]

Sandy, what two bath developer do you like.

[Tyler Boley]

Hi Steve, thanks for providing access to the results of your hard work. As usual your images are lovely. I'm in agreement with you and the others here about this great film...
Bruce's post as well, very informative. I have yet to really nail my film procedures for my Howtek, but even fairly normal zone system practice has been working well, though I might underdevelop from there a bit. With a high density range scanner, it's pretty hard to mess it up. How to find the optimum high density target is the hard part...

Hybrid workflows are yielding really wonderful results these days.
Tyler
http://www.custom-digital.com/

[Ben Syverson]

Not to get off-topic, but what do people usually rate TMY at? I've been shooting it at 200 and am happy with the results, but this thread suggests I could shoot it at 400 and possibly be just as happy.

[venchka]

This information applies to the previous Tmax 400 (TMY) or the NEW Improved Tmax 400 (TMY-2) ?

[sanking]

Sandy, what two bath developer do you like.

Kirk,

Diafine is a good two bath developer for LF. It is a true two-bath formula in that no development at all takes place in Solution A. The stock solutions are also very long-lived.

The Ansel Adams divided D-23 formula (and with variations by Barry Thornton) is also very nice, and gives slightly finer grain than Diafine. But it is not a 100% two bath formula since some development takes place in Solution A, which makes time and temperature control more important than with Diafine.

I am also using the Pyrocat-HD formula as a divided developer for MF film, and it produces negatives of very high acutance.

For many years I used BTZS procedures for testing, exposing and developing film, and this allowed for excellent control with regular darkroom printing. However, if one's goal is to scan and print digitally BTZS type controls are not necessary. These days I just expose for the shadows and develop in a two-bath solution and then adjust tonalities in the scanned image file.

Sandy

[sanking]

Not to get off-topic, but what do people usually rate TMY at? I've been shooting it at 200 and am happy with the results, but this thread suggests I could shoot it at 400 and possibly be just as happy.

Depends on how you meter. With LF I base exposure on an incident reading in the shadows, and rate TMY at EF 400. This gives excellent shadow detail.

When I use the same film with a MF camera with built-in meter I rate TMY at EF 200.


Sandy

[Ken Lee]

You might find this thread helpful: Anybody using Pyrocat-HD or MC as a Compensating Developer? (http://www.largeformatphotography.info/forum/showthread.php?t=52913)

[Bruce Watson]

Not to get off-topic, but what do people usually rate TMY at? I've been shooting it at 200 and am happy with the results, but this thread suggests I could shoot it at 400 and possibly be just as happy.

Much depends on your developer, dilution, agitation method, etc. Enough so you really need to test for yourself to be sure.

For reference, with XTOL 1:3, continuous agitation from a Jobo CPP-2 using a 3010 tank, I get an EI of 500 from 5x4 TMY-2. Clearly, YMMV.

[Steve Gledhill]

This information applies to the previous Tmax 400 (TMY) or the NEW Improved Tmax 400 (TMY-2) ?

Apologies for not making it clear - I'm using the new Tmax400 - "400TMY-2".

[venchka]

Apologies for not making it clear - I'm using the new Tmax400 - "400TMY-2".

Fantastic! So am I. Thanks for all of the great information. Your work is stunning. My feeble efforts need much improvement.

Cheers!

[jp]

Thanks for the testing and verification of what I suspected but didn't do the calculations for.

I believe it. I recently made a few photos at Fort Knox in prospect ME. The interior was seemingly dungeon dark. This cannon was sort of between the interior and a shaded area. I had probably a couple second exposure, I didn't write it down. Outside (through the wall opening) would have been normal bright sunny day, which is magnitudes brighter to say the least. I could see the outdoor detail in the negative, but not on the contact print or quick scan. Scan or print for that outdoor range, and there it is!

There is quite a bit of range available on the indoor exposure too, around the bricks, shadows, rust, bright stone, etc..

This is with TMY2 on my speed graphic / optar 127 lens. The film was processed in straight D76 and scanned on my epson v700.

http://www.f64.nu/photo/tmp/img001.jpg

http://www.f64.nu/photo/tmp/img002.png

[BetterSense]

Cool.

[jim kitchen]

Dear Steve,

Merci... :)

Excellent portfolio, and excellent information regarding your TMY-2 testing, where I will exercise your procedure against my TMY-2, when it arrives.

jim k

[Gary Nylander]

Steve, Thanks for your very informative SBR data in regards to Tmax 400 film, I'm sure many here will find your research very useful, I have been using the new film for the past year or so and really like it.

Gary

[Steve Gledhill]

Thanks everyone for your responses and kind words.

Thinking back on why I posted this, what I really want to conclude is reflected in Tyler's comment affirming the hybrid workflow. Film such as TMY-2 is an amazingly capable medium for information capture. Coupled with digital manipulation available through tools like Photoshop really do give us the opportunity to create images that are at least very difficult if not actually impossible to achieve with an entirely darkroom approach. The hybrid approach is definitely for me. Please don't take this as me trying to whip up conflict of the digital vs darkroom type - I'm not. I'm speaking just from my own personal experience which led me after 25 years of producing prints in the darkroom to give it up. I was personally unable to carry out darkroom work to my satisfaction. I did manage a few good prints along the way, but not many in proportion to the effort I expended. But soon after stopping darkroom work I found that I could scan my negatives and work on them with Photoshop. So about 8 years ago my enthusiasm was rekindled by this hybrid workflow and I've not looked back since. It has been a long learning curve but satisfying and rewarding at every stage.

[BetterSense]

...Photoshop really do give us the opportunity to create images that are at least very difficult if not actually impossible to achieve with an entirely darkroom approach.
You are absolutely correct, a hybrid approach is a very different tool and can do things that are fundamentally impossible to achieve with physical tools. The flip side is that the 'entirely darkroom' approach itself can produce objects that are fundamentally impossible to achieve with digital. There is no news here. That there exists some thing that a medium cannot do, is not an automatic demerit, else nobody would use any media at all; all media have things they cannot do. Media are media and their qualities are their own.

[Ken Lee]

Archival inkjet prints ?

Inkjet prints free of metamerism ?

Inkjet prints free of out-gassing ?

[Oren Grad]

Diafine is a good two bath developer for LF. It is a true two-bath formula in that no development at all takes place in Solution A. The stock solutions are also very long-lived.

With apologies if this is going off on a tangent - what is your agitation procedure for sheet film in Diafine to achieve even development?

[Vaughn]

Just thought I'd toss this in the mix.

My Pentax digital spot meter read 13 stops -- 0 in the darkest, 13 in the brightest...but since it read 0 in the darkest areas, I don't know how far below 0 it actually was (I exposed it at 2). So I under-exposed the shadows probably. The scan of the print show less detail up there than the print has, but the neg is clear in some of those areas up there.

On Tri-X (the older stuff, 5x7), developed for the "normal" time in HC-110. Straight print -- but it is a carbon print. One of the reasons I like carbon printing is its ability to reproduce that sort of SBR.

Vaughn

[sanking]

With apologies if this is going off on a tangent - what is your agitation procedure for sheet film in Diafine to achieve even development?

Oren,

I prefer to develop sheet film in Diafine with rotary agitation in tubes or Jobo. If you read the Diafine instructions you might be led to believe that constant agitation will not work, but I found that it works very well. I dilute both A and B solutions 1:1 to compensate for the greater agitation and develop for the same amount of time. In practice I find that this gives the the same contrast as developing with the full strength solution with intermittent agitation for the same time.

One of the things I like a lot of about Diafine is that gives a very long and straight toe, even with films that typically are not very linear, TRI-X 320 for example. S in addition to being able to capture a very long subject brightness range two bath development with Diafine also gives very linear results from the shadows to the highlights.


Sandy

[Oren Grad]

Sandy - thanks, that's very helpful. Yes, because of how the instructions are worded I've wondered how Diafine would fare in rotary development. Sounds like it's worth a try.

[SW Rick]

Sandy,

with the diluted Diafine, do you then use it on a "one-shot" basis, or can you reuse it?

Thanks for the suggestion!

Rick

[Steve Gledhill]

Archival inkjet prints ?

Inkjet prints free of metamerism ?

Inkjet prints free of out-gassing ?

Ken,

I didn’t intend for my post to go beyond the creation of the image into the medium used for displaying an image and into the matters you’ve just raised. Clearly what you’ve alluded to are very important matters indeed. But, for me personally (that is the basis of my post), I am more concerned about the here and now rather than the long term life of any of my images. For me the ‘here and now’ is about the current enjoyment of an image whether it’s displayed on the web or printed. And for me my current means of display – ink prints and the web – satisfy my requirements. My ink prints display next to no metamerism, next to no gloss differential, are likely to last for my lifetime and a good deal longer. So, for me, that’s good enough to be able to show my work to others and to feel a sense of pride and achievement. I know full well that for others, for personal, aesthetic or commercial reasons, that’s not enough.

[Steve Gledhill]

You are absolutely correct, a hybrid approach is a very different tool and can do things that are fundamentally impossible to achieve with physical tools. The flip side is that the 'entirely darkroom' approach itself can produce objects that are fundamentally impossible to achieve with digital. There is no news here. That there exists some thing that a medium cannot do, is not an automatic demerit, else nobody would use any media at all; all media have things they cannot do. Media are media and their qualities are their own.

BetterSense talks good sense. As long as you don't think I was attempting to "demerit" any other process. So, as you say - "no news here". As in my response to Ken, I'm speaking of my own experience. Just for the record, I see fabulous work from the darkrooms of others and marvel at their techniques that I could never master despite years of trying.

[Doremus Scudder]

Steve,

Great work!

And, as to the digital vs. traditional darkroom debate... Looking at your work, done with the hybrid process, often gave me the eerie feeling that I was looking at something of mine that had slipped my mind.... with 100% wet darkroom techniques.

The techniques are just tools, with inherent limitations and advantages that need to be learned; it is one's vision that is most important.

Best

Doremus Scudder

[BetterSense]

with the diluted Diafine, do you then use it on a "one-shot" basis, or can you reuse it?


I've never done it myself, but the one person I know who diluted Diafine used it one-shot. To me it seems like a waste of Diafine since a liter of the stuff lasts me for years, but I suppose in the final analysis it's not terribly expensive afterall.

[sanking]

Sandy,

with the diluted Diafine, do you then use it on a "one-shot" basis, or can you reuse it?

Thanks for the suggestion!

Rick


Rick,

You can definitely re-use the diluted Diafine several times if you do so the same day or within a window of a few days. Whether the diluted solution will keep as well as the standard stock I can not say because I have not tried to use it that way. In any event it is fairly economical to use one-shot and discard considering the relatively small amount of solution that is used in rotary processing in tubes or drum.

Sandy King

[chris_4622]

Sandy,

Does Pyrocat HD have a compensating effect when used in Stand Development?

chris

[sanking]

Sandy,

Does Pyrocat HD have a compensating effect when used in Stand Development?

chris

Chris,

Only with very weak dilutions.

Sandy King

[Stephen Willard]

Steve, I notice that your PDF only showed 14 stops and not 18 stops as advertised. Maybe I was missing something when I looked at it.

I am curious, has anyone taken density readings of their film test strips and plotted a characteristic curve for your different developers and processing methods. It is one thing to get 14, 18 or 22 stops of dynamic range, but if the curve has a pronounced toe and shoulder, then perhaps the claims are really not what is actually happening. There is a big difference between a 18 stop straight line curve and 18 stop curve with exaggerated toes and shoulders. The form is much preferred because the clarity of detail in both the shadows and highlights is far superior.

I work with color negative film and the curves I get from the film and developer I use is almost a perfect straight line with a slight shoulder at Zones XIII and XIV. There are color negatives films I have tested that lack straight line curves and the difference are very apparent. The detail in the shadows and highlights look flat and dull compared to the film I am using. Of course, it is hard to see until you put both prints side by side and then it is amazing just how much more brilliant the detail is in both the shadows and highlight are with a straight line curve.

Curves in the b&w world that have noticeable toes and shoulders would exhibit different levels of contrast as you move along the curve, and thus, would make it difficult to match a paper contrast grade to the print. With curves that have noticeable toes and shoulders, the contrast at those points would be softer then in the mid tone sections. With a straight line curve, the contrast remains constant at all points of the curve, and thus, would be a better match for a paper contrast grade. Clearly, since I do work in b&w then my observations and opinions are just guesses.

Any responses would be appreciated.

[Brian Ellis]

You are absolutely correct, a hybrid approach is a very different tool and can do things that are fundamentally impossible to achieve with physical tools. The flip side is that the 'entirely darkroom' approach itself can produce objects that are fundamentally impossible to achieve with digital. There is no news here. That there exists some thing that a medium cannot do, is not an automatic demerit, else nobody would use any media at all; all media have things they cannot do. Media are media and their qualities are their own.

Just curious - when you say there are "objects" fundamentally impossible to achieve digitally that can be achieved in the darkroom, what do you have in mind? I ask because after about 15 years in a darkroom and about 10 printing digitally, I haven't found anything I did in a darkroom that can't be duplicated digitally (though my goal has never been to just duplicate what was done in a darkroom, my goal is to do better than that). But then I probably didn't do everything possible in a darkroom so I'm wondering what you're thinking of.

[BetterSense]

I haven't found anything I did in a darkroom that can't be duplicated digitally
No doubt. There's little that can't be duplicated, relicated or mimic'd digitally. But just because a process in the darkroom has a digital analog, doesn't mean the digital version is the same. Thats' not to argue either one is better than the other. The main thing you cannot dodigitally is make traditional darkroom prints. If you made a darkroom print with the computer, it wouldn't be a darkroom print anymore, see? It sounds like a silly argument, but it's actually a very important one, I think. You might say that you can do everything with acrylic paint that you can do with oil paint, but you would be wrong, because you can't make oil paintings with acrylic paint, quite by definition.

[Steve Gledhill]

Steve, I notice that your PDF only showed 14 stops and not 18 stops as advertised. Maybe I was missing something when I looked at it.

Stephen,
I'm at a loss to understand - the PDF shows from the top a Blank strip (black) + a Zone -2 strip + a Zone -1 strip + a Zone 0 + strips for Zones 1 to 14 making 18 in total. If you can't see them all then something must be happening to truncate the display of the pdf on your monitor. If you can see the words but not distinguish the tones for the 4 zones at the top of the pdf then that's a problem with the calibration of your monitor.


I am curious, has anyone taken density readings of their film test strips and plotted a characteristic curve for your different developers and processing methods. It is one thing to get 14, 18 or 22 stops of dynamic range, but if the curve has a pronounced toe and shoulder, then perhaps the claims are really not what is actually happening. There is a big difference between a 18 stop straight line curve and 18 stop curve with exaggerated toes and shoulders. The form is much preferred because the clarity of detail in both the shadows and highlights is far superior.

I personally haven't taken density readings but it is clear that there is a toe and a shoulder. I didn't suggest this is all linear. I'm not sure what you mean by "perhaps the claims are really not what is actually happening".

[Ken Lee]

Correct me if I'm wrong, but we view density curves on a logarithmic scale. So what we loosely call "linear", is not really so. I wouldn't be surprised if the human eye itself, responds logarithmically, rather than arithmetically, to light.

According to my (limited) studies of music theory, the human ear doesn't respond to sound in a linear manner, because the sensor mechanism involves a logarithmic spiral. Hence all the effort and compromises involved in making "well-tempered" musical instruments, which will play nicely in different keys.

That aside, the tests you can see with Divided Pyrocat HD (http://www.largeformatphotography.info/forum/showthread.php?t=52913), show that the visual data is readily available, and doesn't need to "decompressed" out of a compressed shoulder area.

[ronald moravec]

Digital has provided something wonderful called HDR. Nothing prevents you from making 3 to 7 negs with correct exposures for the shadows to highlights on differing neg. Scan and assemble with HDR software. Note you do not have to make things looks like a cartoon. Be tastfull. And scan them all as a neg with normal exposure.

thelightsright studio has a digital digital darkroom tab underwhich ther is a nice video of extented range where you combine files with the luminescent mask and not HDR.

http://www.thelightsrightstudio.com/tutorials-video.htm

See the one on blended exposures. Remember you can work 4/5, then 3/4 then 2/3 and finally 1/2 in steps

This is a really nice procedure I use for night shots.