Need help using zone system with film with 19-stop dynamic range

[Bill Burk]

Stephen knows his stuff and lays out the science with precision and has caught me in a few imprecise uses of terminology that I correct as I go forward.

Drew knows his stuff but presents it like a storyteller kicking another log into the campfire.

I missed the Moose wandering just down the road at Vedauwoo and wild horses at Angel Creek, but if it weren’t for the storytellers I met I wouldn’t know either existed.

 

[DREW WILEY]

Actually, I'm sensitized to wood smoke due to having already survived several major forest fires. But yesterday I did take a shot of an old campfire pit at dawn due to its fascinating hues, and some black and white shots of a the burn area from an enormous fire last year. But I don't want to put everyone asleep like a Joe B. speech, though I personally needed a good nap the last round (don't try to read any political leanings into that, cause that's not what I'm implying).

But let me give the ole boomerang at least one more try. All this talk about ASA, ISO, and EI basically concerns interpolating and extrapolating basic curve characteristics using various geometric shorthand math ploys suitable for marketing and general usage classification purposes. Fine; it needs to be done and properly differentiated. But every bit of all that is based on characteristics curves themselves, which are the real standard of definition and ultimately the authoritative "horse's mouth" one needs to consult. And how do you deal with curves per se unless you're into integral calculus? - and to somebody like me, that implies a painful visit to the dentist. So I prefer a visible graph form, but in more detail than most.

But again - let's take just a single example of a film / developer combination, both exceptionally flexible - TMX100 and HC-110. Even the published curve is just a representative example of an assumed common scenario. If you factored in numerous potential variables of developer concentration and outcomes in a very wide range of anticipated contrast levels or gamma, and that in relation to a wide range of exposure times in relation to a variety of b&w contrast filters, including long exp recip characteristics and how those potentially differ in each case from normal times, you'd literally need at least a hundred different curve plots just to discover a realistic pattern. No single curve would work. Arcane? Not if you're making color separations with TMax, which is one of the specific applications it was specifically engineered for at the beginning. I realize that few chiming in on this particular thread are into that, but the fact itself tells you a lot about TMax and how it differs from most other films.

Although the Zone System is largely in the rear view mirror for me personally, there is no single zone system, but many variations depending on either the guru or even the individual photographers himself. It was designed to be somewhat plastic, according to personal expectations and needs. So some of the hard-boiled stereotypes about it on this particular thread tend to be misleading. Always 2/3 stop off? Nonsense, for the very reason I just explained.

Don't get me talking about wandering moose-moosies either (why aren't they called meese?). I had set up a sunset shot in the Wind Rivers right atop what I didn't realize was a moose trail. Then one and its calf suddenly showed up and I had to quickly grab the 4X5 to get it out of the way, then try to rapidly recompose before all the clouds and light were gone mere seconds later. But the tripod had been tipped over by the moose. No time to refocus. Lucky I guess, but just a tiny bit of swing was affected and I got some great prints, but with just a little bit slightly out of focus on one lower corner. My hiking companion has digital camera proof, and that a "Whaaaat is thaaaat giant deer?" incident did occur.

 

[Vaughn]

Drew -- the 16x20 has some sky -- and on TMax100 (taken Dec.1990), but with a slight overcast that still allowed the sun to produce nice open shadows...so only a nice 5 or 6 stop range. Difficult light to stumble across in the Sierras, lovely when one does.

I got surrounded by a harem of elk in the redwoods in the middle of a ten-minute exposure. The bull showed up and made nasty noises at me -- my 8x10 disappeared into its pack...kinda of amazing, really. I climbed over a couple fallen redwoods and that seemed to satisfy the guy.

 

[DREW WILEY]

Takes me back to my first face to face look at a mammoth plate contact print of El Cap by Muybridge. Same kind of light, but no snag in the foreground. I used a bit of veiled smoke lighting coming up the canyon into the upper reaches of the Merced a few years back for a very silvery high key rendering of that high altitude total-solitude version of Yosemite. Little detail was obscured by the haze except on one distant peak. The foreground was in deep shade and had the counterpoise of rich deep gradation plus sparkling stream reflections, fun to print.

My worst critter encounter was when I had my head under the darkcloth composing with the biggest manzanita I've ever encountered, an amazing color shot. I heard a bunch of grunting and looked around, and a herd of over 20 wild pigs was surrounding me, including four boars, trying to figure out what kind of critter I myself was, with five legs, three of them maple.
I was about to grab my Ries tripod by the neck and climb a tree if needed, but went ahead and bagged the shot. In the meantime their grunts of perplexity started turning into grunts of actual communication to one another. So I had to act fast, and started loudly whooping and hollering, hoping to confuse them. It worked, and they all started running around me the same direction in a big circle, and then all suddenly took off together.

A more comical encounter was when Pt Reyes still had some big Ibex left over from its days as a hunt club around Limantour Estero. One Ibex was terribly curious what kind of creature had five legs, yet just one big eyeball. Yet he was terrified at the same time, so kept inching closer and closer to get an eye-to-eye look, trembling the whole time. Suddenly, maybe only two feet away, he let out a huge belch, scared himself, leapt way up, and ran off. I've had wild red foxes and coyotes come right up to me when using a tripod, and just sit down beside me until they finally figured out that whatever I'm doing, it's just plain boring to them. Then they just casually wander off.

 

[Stephen Benskin]

I don't use personal ASA, ISO, EI, Zone System, or Beyond Zone System. All of that is too crude for my own purposes. I'm visualizing the specific shape and placement of the curve itself every shot, tailored, even though now it's almost entirely intuitive and instant due to sheer familiarity. Has it made a real difference right into the look of the prints themselves? Absolutely. Just yesterday I was in an intense forest fire burn zone - the most dramatic fire in the world last year. Talk about lighting extremes! It was a rush trip so I just grabbed the bag and tripod. Had only 4 frames of TMX left in the 6X9, plus an unopened roll of Acros. Merely adjusting the rating of the ACROS down to 50 won't make it equal to TMY @ 100. Different animals.I wasn't dealing with just shades of gray, but black upon black upon black, juxtaposed to shimmering highlights. I knew exactly what to do when I switched rolls.
I have a pretty darn good BS meter too, Stephen, and have no interest in jousting with your own ridiculous assumptions about me. Got better things to do than to play ego games. My own methodology might or might not help others. It's there if someone happens to need another option more precise than the usual suspects. But don't attack something you obviously don't understand yet, and apparently don't want to. Welcome to my ignore list.

You beat me to it. But before you go, could you explain how photography is like music?

 

[Stephen Benskin]

Peter,

There is no direct correlation between specific negative density values and print tones. The negative is the intermediate step between the subject and the print. The idea is to record the luminance values of the subject in a way that produces a print that is regarded as having good quality. Generally that means developing the film to where the resulting negative density range will fit on the paper's Log Exposure Range (LER). Exposure places the camera image of the subject Luminance range on the film where the is sufficient separation of the values. Loyd Jones determined that one of the factors that determines a quality print is tonal separation in the shadows. This point has a gradient of 0.3 times the overall gradient of the film Below this point, quality drops off. Above this point, there is no significant drop in quality for a number of stops and then other factors, such as higher grain and reduced sharpness, begin to influence quality. The amount depends on the film format and degree of enlargement. That means 35mm will have the least amount of tolerance to additional exposure.

The statistically average scene is 7 1/3 stops or 2.20 logs. This does not include accent black or specular reflections. By placing the shadow exposure as low on the curve as possible while keeping it above the minimal useful gradient, sharpness is maximized and grain minimizes. Plus printing times are lower. Printing times, as well as sharpness and grain, increased in importance as smaller formats became increasingly popular. Without the limiting factors, theoretically an exposure could be placed anywhere there on the film where there is a sufficient gradient. This means anywhere between the limiting shadow gradient in the toe of the film and a limiting gradient in the shoulder of the film. If there are 10 stops between these two points and the film has a 7 stop range, that gives a 3 stop exposure latitude. The 7 stop exposure can be placed anywhere within these ten stops and still have good reproduction of tones. This is where the 19 stop range of TMX comes in. For the 7 stop scene, the TMX film would have an exposure latitude of 12 stops.

D. Connelly has an excellent definition of exposure in his paper Calibration Levels of Films and Exposure Devices. "The validity of the exposure determination method must, therefore, depend upon the ability of the resulting photographs which are produced by substituting a single value of luminance determination of exposure to represent the multiplicity of values of luminance of the scene itself. From the point of view of the film, satisfactory photography depends upon the proper location on its exposure density characteristic of the densities produced by the image illumination within the camera. The greatest and least significant luminances in the scene are required to cause exposure of the film within the usable part of its exposure density characteristic. This implies that the most important characteristics of the luminance are:

1. the ratio of its maximum to it minimum value
2. its absolute value of maximum or minimum.

For the former determines whether or not the film can reproduce the contrast range of the scene and the latter determines the exposure time necessary to provide an exposure which will locate the brightness scale o0f the scene correctly relative to the film characteristic."

When making an exposure, you can only use a single shutter speed and f/stop combination. This means only a single point of exposure can be known and determined. The rest is assumed. It's sometimes called place and fall or peg and fall. According to Jack Holm, "the mean log luminance of a statistically average scene is approximately 0.95 log units below the highlight log luminance and 1.25 log units above the shadow log luminance." This is the assumption for the exposure placement that the ISO speed rating is based upon. But what if the scene isn't statistically average? What if the shadows aren't that deep or are deeper. Some will say that is where spot metering and systems like the Zone System come in. They remove the assumption of the range of the shadows.

The current ISO speed method allows for approximately a 1/3 stop safety factor based on the above assumption. An average flare factor of one stop increases the potential safety factor but flare is inconsistent from subject to subject. A scene with zero or low flare will result in the shadows falling at or near the limiting gradient point in the shadows. Some people don't like having their exposure so close to the minimal point, so they apply an additional safety factor, which is simply compensated for in the printing if necessary.

There is nothing wrong with this. Before the 1960 change in the b&w film standards, film speeds were 2/3 to one stop slower for a given film. This was the result of a different way the speed was calculated. A safety factor was incorporated into the speed rating because of the lack of people owning meters and the inefficiency of the meters that existed. So reducing the speed rating of a film by 2/3 stop only brings it into agreement with the pre 1960 speeds. It doesn't adversely affect quality in most cases.

To be clear, the above graph is an evaluation based on the pre 1960 speed method which was a time when lenses had a higher flare factor. For reference, the graph below reflects the post 1960 standard and less flare. Please note the difference between (5) Statistical Average scene and equivalent grey calibration surface for photoelectric reflected light meters and (4) Fixed density film speed computation point.

And the next graph compares the ratios of the Zone System and ISO speed point and the metered exposure point. The lxs values are for 125 speed film. 0.8 / 125 = 0.0064 lxs. This is where the 2/3 stop discrepancy between ISO and Zone System speed comes from.

 

[Paul Ozzello]

This is where the 19 stop range of TMX comes in. For the 7 stop scene, the TMX film would have an exposure latitude of 12 stops.

Very interesting post. So tmax 100 really has 19 stops of dynamic range ? Concretely what does this mean if you meter a scene with a Pentax digital spotmeter ? Should one meter the shadows and place the EV reading on RLE 1 like @Lachlan Young suggests and just let everything else fall into place ? Or since there is so much latitude should shadows be placed a little higher up on the scale ? Or is that the whole point of rating the film 1/2 - 2/3 of box speed ?

paul

 

[Lachlan Young]

Very interesting post. So tmax 100 really has 19 stops of dynamic range ? Concretely what does this mean if you meter a scene with a Pentax digital spotmeter ? Should one meter the shadows and place the EV reading on RLE 1 like @Lachlan Young suggests and just let everything else fall into place ? Or since there is so much latitude should shadows be placed a little higher up on the scale ? Or is that the whole point of rating the film 1/2 - 2/3 of box speed ?

paul

IRE 10 ('1' on the Pentax) is effectively giving a 2/3 stop exposure bump compared to ISO standards - rather than placing shadows at 3 1/3 under the nominal mid, it places them 2 2/3 under - so it's effectively giving the notionally more detailed shadows/ safety factor that the zone system folk work so hard at getting without all the wasted time/ effort. It isn't perfect, but for most people wanting a workable solution with more guaranteed detailed shadows under real-world variable flare conditions etc & within the latitude of the material used, it's very effective. You can also get to the same end point with an incident meter.

 

[warden]

Nice light...

That’s a fine image, Vaughn. Thanks for sharing that.

 

[Paul Ozzello]

IRE 10 ('1' on the Pentax) is effectively giving a 2/3 stop exposure bump compared to ISO standards

So using the RLE scale then I should set the meter to box speed ?

 

[Vaughn]

Thank you, the print has a raised relief, so unfortunately one can't see how the snag rises above the surface of the paper (5x7 carbon print). It is nice to toss an image in with the discussion every once in a while.
It took me another 25 years or so to finally make another image with that rock face as a 'sky' -- a 5.5x14 platinum print I made two months ago.

 

[DREW WILEY]

The IRE scale was mainly for sake of the movie industry determining the parameters of COLOR film relative to mid 18% gray. It has little to do with black and white applications, which, if you understand any of this, extends past that range both directions in most cases, except perhaps Pan F, which has about the same comfortable range as most color chrome film. Yes, you can adopt the same convenience on the dial for b&w shooting if you don't yet know how to properly meter for shadows versus highlights, which takes about five seconds longer to do with the very same spotmeter.

Fatso - you're still 90 miles away from being correct about any of this. Take a deep breath, slow down, and realize, first, NO, you do not get anything remotely like 19 stops of exposure out of TMax. And no, a spot meter will not cause that to somehow miraculously happen. It will facilitate taking precise readings from discrete points in a scene (shadows vs highlights vs mid-tones), allowing you to quickly compare those respective values and more intelligently distribute the scene contrast onto what a given film can realistically handle. But nothing will substitute for taking your results and testing them in the darkroom relative to actual prints. That's how one truly learns what the meter is capable of doing.

 

[Paul Ozzello]

Yes, you can adopt the same convenience on the dial for b&w shooting if you don't yet know how to properly meter for shadows versus highlights, which takes about five seconds longer to do with the very same spotmeter.

What do you suggest ?

 

[Lachlan Young]

So using the RLE scale then I should set the meter to box speed ?

Yes - though I'd suggest doing a small set of exposure brackets (-1/3, -2/3 etc) too - everyone has different tastes for 'correct' shadow placement & only you can be the judge of that.

 

[DREW WILEY]

Well, if it were me, I would go out and find a decent used Pentax digital spotmeter. They're extremely intuitive to use once you get accustomed to them. But they're no longer made, and examples in mint condition can be somewhat expensive, but not always - it takes some luck. You position your chosen point readings on the scale of the dial with a simple twist, and a single glance tells you where all those values fall in relation to one another, as well as in relation to the exposure triangle. There are separate adjustable rings aligning your exposure speed and f/stop. No fancy buttons or flashing lights; reliable. After that, just practice with it a lot till you're comfortable with the concept.

Other people can champion their own preferred manner or meter. But the whole point is that you have more valuable information at hand than just an average of midtone values, which might be fine for many color film applications, but doesn't tell you what you most need to know for high-quality black and white exposures - where your threshold of shadow texture above pure black actually is, versus where your highlights lose texture at the opposite end of the scale into pure white. This is an oversimplified explanation, but deliberately so. Get to first base first.

Onboard TTL camera programs and matrix metering won't do that for you; they work on statistical probability, like an auto-piloted car without a real driver in control.

Otherwise, there is simply no substitute for bracket testing when learning where to set your film speed, like Lachlan just interjected. I'd take a roll and start at half the box speed, then work your way up on separate frames to maybe an equal amount above box speed, then study the results after the film is developed, and hopefully print a few frames to find out which exposure setting is best for you. It's an ongoing learning curve as one keeps practicing. You'll get there.

 

[Paul Ozzello]

Well, if it were me, I would go out and find a decent used Pentax digital spotmeter.

I have a Pentax digital spotmeter but I always favor my Minolta Flashmeter V in incident mode. I also have one of those zone stickers lying around somewhere but I liked Lachlan‘s suggestion of using the built in RLE scale.

I’d like to use the basics of the zone system but without getting into plus and minus development (except for specific lighting situations like whiteout snow). I always assumed tmax and delta100 had roughly 13 stops of dynamic range - how is it some people are getting 19 ? Using a low contrast developer ? I drum scan my negatives and make Piezography prints so I won’t be using my darkroom anytime soon...

Is there really much else you can do besides expose for the shadows without compensating film development times ? Shadow readings should either be placed on zone II or III and if your highlights measure above zone VIII then you need to decide whether the shadows or highlights are more important and place the other zones on the heel or toe of the film curve. What else am I missing ?

For determining the proper film speed - is there any other tool I can use to measure film density without getting an expensive densitometer? Would a colormunki work ? My ilford EM10 ? I still have an old Jobo Colorline for Cibachromes...

 

[Paul Ozzello]

First (off topic), how long have you been using Piezography? I've been on the fence for a while but have been seriously considering it.

Hi @michael_r - I’ve been using the Piezography pro inks it for two years now. I’m in the middle of printing some large format prints 30” x 72” for an upcoming show - I think you’re in Montreal right ? You’re welcome to come by the studio to have a look. Send me a PM.

Some people really like to complicate things. I’ll keep it simple and meter for the shadows and alter development only when absolutely necessary.

Paul

 

[DREW WILEY]

fatso - if you are more comfortable with an incident meter, that fine; but "spot"meters are intuitive for small spot shadow readings. There's no need for a silly zone sticker. If you want to use either speed of Tmax with respect to Zone System jargon, do NOT place shadow values above Zone 2 ; you'll risk blowing out the highlights in any high contrast scene. But in balanced studio lighting or other softly lit settings, life gets easier, exposure-wise; but in that case you don't need a high-performance TMax Ferrari either.

Don't try very low contrast development either. Notice how Michael's curves look darn good reasonably developed; but the experimental very low-contrast curve is quite squirrelly. One of these days I'll throw him a life raft containing my own low contrast tweak, which has an excellent straight line; but unless someone is doing unsharp masking, I don't see any practical need for it. But you seem to be on the right track, and if you yourself need to "complicate" things a bit more, then you can cross that bridge when you come to it. Good luck with your show!

 

[Alan Edward Klein]

fatso - if you are more comfortable with an incident meter, that fine; but "spot"meters are intuitive for small spot shadow readings. There's no need for a silly zone sticker. If you want to use either speed of Tmax with respect to Zone System jargon, do NOT place shadow values above Zone 2 ; you'll risk blowing out the highlights in any high contrast scene. But in balanced studio lighting or other softly lit settings, life gets easier, exposure-wise; but in that case you don't need a high-performance TMax Ferrari either.

Don't try very low contrast development either. Notice how Michael's curves look darn good reasonably developed; but the experimental very low-contrast curve is quite squirrelly. One of these days I'll throw him a life raft containing my own low contrast tweak, which has an excellent straight line; but unless someone is doing unsharp masking, I don't see any practical need for it. But you seem to be on the right track, and if you yourself need to "complicate" things a bit more, then you can cross that bridge when you come to it. Good luck with your show!

What do you mean high-performance Ferrari?

My main interest, since I don't use the zone system or developed myself, is to get the best range of tones to maximize the flexibility I have afterward to adjust how I want the scan and/or print to look. Does that make Tmax 100 and 400 the best films to use?

 

[DREW WILEY]

Ferrari analogy : TMax is a high-performance film. You don't want to lean on the accelerator too hard; and you need to be especially attentive steering if you are going fast. It has less forgiveness than many of other films. But it can sure take you places!

Alan - try not to overcomplicate any of this. In your case, if just 4X5 format is what is in question, I'd stick with TMY400, and not worry about TMX100. You'll get better edge acutance, and the grain will still be plenty fine for most purposes. Plus it's two EV faster to shoot, making life easier on breezy days.

 

[Helge]

AFAICS you have to be really off, to miss-expose TMax 100.
I’ve gotten very good prints and scans that looked like they where exposed at least two or three stops over and under.

Sure, it’s not the insane “set a random shutter and aperture and get a printable photo” guarantee as with HP5 or TriX, but then the resolution and smoothness is orders of magnitude higher with TMax.

 

[DREW WILEY]

Depends on your lighting conditions and what you're standards are. And realize the characteristic curve doesn't lie. It tends to be steep; and underexpose a bit too much and you fall off a cliff into blackness. I've deliberately done that in certain instances just to get a blank unambiguous graphic black. But because I knew the precise threshold of that, curve-wise, it was entirely predictable. Do you print digitally too, Helge, or in the darkroom?

 

[Helge]

Depends on your lighting conditions and what you're standards are. And realize the characteristic curve doesn't lie. It tends to be steep; and underexpose a bit too much and you fall off a cliff into blackness. I've deliberately done that in certain instances just to get a blank unambiguous graphic black. But because I knew the precise threshold of that, curve-wise, it was entirely predictable. Do you print digitally too, Helge, or in the darkroom?

It depends very much on lighting of course.

In low light you will always use either a flash or a tripod.
So it’s almost implicit that you’ll consider metering carefully or have it done for you by the flash.

In daylight however in the about six stops from bright sunshine to sunset/deep shade you’ll have room to just measure once, go by sunny 16 and adjust to experience, and have good negatives.

Optimal? Of course not, but plenty good to honor the film and get deep shade and highlight detail.

And yes I print and scan. I practically only scan to use on a screen though.
Much prefer projection and wet print.

 

[DREW WILEY]

Try that formula in harsh desert or mountain lighting and you might be disappointed. Of course, after a lot of practice with metering and printing, we just sorta learn through sheer experience anyway, and often know exactly what to do, regardless. I've even accidentally dropped my spotmeter into cold snowmelt streams a couple of times, and continued photographing, and got perfect exposures even with color chrome film, simply because I understood the light values from memory, having taken so many analogous scenes before. Luckily, in both instances, I was able to successfully dry out the meter after the trip. When I started photography as a teenager, all I had was an early Pentax H1 with an externally coupled CDS averaging meter. Once I got used to it, all I shot for years was Kodachrome, and can't remember ever goofing a single exposure. So maybe in this whole metering topic we should include our own memory and intuition as the most important equipment. All that really counts is the end result.

 

[Paul Ozzello]

do NOT place shadow values above Zone 2

Assuming all my equipment and thermometers etc are accurate - exposing shadow detail on zone 2, and assuming tmax has 13 stops of useable dynamic range (between shoulder and toe) shouldn’t I be able to correctly expose a scene with 9evs of SBR ? And if I have less than 9 should I bump everything up the scale and place shadows on zone 3 or even 4 ?


Or is the rule instead - no matter what, ALWAYS place shadows on zone 2 - and compensate by contracting or expanding development.

Good luck with your show!

Thanks ! I’m loving these gigantic prints