Too many Zones?

pete_andrews · June 27, 2000

First off, let me say that I'm not a disciple of the zone system. I'll go along with the underlying philosophy of pre-visualisation, but IMHO there are more intuitive ways of getting there. I favour incident light measurement, coupled with compensation for the specific subject to be photographed, or effect to be acheived; so my question is really aimed at devoted users of the zone system.

The reference point in the zone system (and for the calibration of exposure meters for that matter) is stated as being "mid grey", zone 5, or 18% reflectance. Now 18% reflectance is only two-and-a-half stops down from a theoretical 100% reflecting diffuse surface, which one would expect to be rendered very near flat white in a print. A whitewashed wall comes close, for instance, and this isn't even Zone 8, so where do the higher zones fall? It seems to me that zones higher than 8 are only of relevance if a source of illumination or specular reflection is included in the picture, and we are willing to let objects which should normally appear near-white in the print slip down the scale to grey.

These days, you can't even expect the film to compress the highlights by flattening off toward maximum density. If you look at a film like T-Max, or even Plus-X developed in T-Max developer, the density curve just keeps going up and up in a straight line, putting the densest highlights well beyond the range of the toe of the paper curve. Remembering that the zone system was thought up when a typical film (or plate!) had an "S" shaped curve.

The conventional zone system answer to this is to add even more zones beyond 10 to accomodate the wider density range, but how are these extra zones to be accommodated in the print? Reduced development and contrast will simply make our prints look flat. The only answer that I can see in reality is to burn the highlights and/or dodge the shadows. What do you do with a contact print?

How many users of the zone system regularly make use of zones more than plus or minus one stop from the "norm"? I'll confess that most of the time I end up exposing within a stop of what the incident light meter recommends. How about you zone system users? I'd be interested to know how much the "expert" exposure deviates from the idiot-guide on the leaflet included with the film (i.e. June to September, cloudy-bright - 1/125th at f/8).

william_marderness1 · June 27, 2000

It is possible to get an S-shaped curve with today's films, but not

with T-Max developer. Most developers produce a straight-line curve,

but some give an S-shaped curve. D-23 gives a shoulder with HP-5+

that begins around Zone 7. Microdol-X should do the same, since it is

basically D-23, but with the addition of sodium chloride, a silver

solvent.

I have tested the HP-5+/D-23 1:1 combination for N-4 through N+2

development. N-4/N-3/N-2 is great for extreme contrast, which is

rather common in outdoor photography. I have used N-3 to photograph

architecture with one side of the building in bright sun, and the

other in shade. N-2 and N-1 are great for portraits, since they lower

the contrast and hide blemishes. N+1 is useful for low-contrast

situations like fog. I often use N+2 for alternative processes. I

would say about 30% of my shots get N development.

sergio_ortega · June 27, 2000

Pete,

Most Zone System followers use a spot meter, not an incident light

meter. Additionally, Zone System controls come into play not in the

initial camera exposure settings, but rather in the

subsequent development the film is given later. The initial camera

exposure settings will only vary slightly for typical Zone System use,

the subsequent film development will vary much more.

At the risk of oversimplifying, the Zone System can be briefly

summarized as follows: "expose for the low values, develop for the

high values". The key to this is that the high values in the negative

respond much more quickly to increased or reduced film development

than do the low values.

Before putting the Zone System to use, initial film testing should be

done to determine your particular exposure index (EI) for the specific

film/developer/meter/lens shutter combination you've chosen.

Additionally, Zone System testing should be done to determine your

N(ormal), N-1, N+1, etc. film development times.

There are a ton of books/guides available describing this initial film

speed test, and the subsequent testing procedures to detemine film

development times, so I will not go into it here. However, a

densitometer is almost a necessity to perform these tests.

In short, you should determine the specific film EI you should use to

yield a net Zone I density in your negative of between 0.08 to 0.11

(or so), so this density can consistently be reproduced in your

negatives during the initial camera exposure. This film speed test

should be done for every film/developer/meter/lens shutter combination

you anticipate using.

Subsequent development time tests for N, N-1, N+1, and so on, are more

involved, and should be conducted taking into account your own

printing equipment, light source, printing paper/print developer,

personal tastes, and a whole host of other considerations.

I'll briefly describe my own procedures for using the zone system:

1. I will spot meter (Pentax Zone VI) a scene initially, to determine

the actual range of values in the scene. This initial evaluation will

tell me what I can ultimately expect when doing a more detailed and

specific measurement of the scene.

2. I'll then look at the important low values in the scene, to

determine which ones should be metered, and where they should be

placed on the Zone scale. This low value placement will determine

my camera exposure settings.

Let's take a typical landscape scene, with a full range of tonal

values. I'll first place the important low values--those low values

where I want to retain full texture/information in the final print,

and not have them print as non-textured/non-detailed, blank dark

areas--on a Zone III or IV.

This will be my starting point in determining camera exposure. Often,

an incident reading, taken in the same light, will yield a very

similar exposure recommendation.

3. I'll then look at the highest important values in the scene, meter

them with the spotmeter, and determine where they will fall in

relation to the Zone III-IV placement of the important low values.

For illustration puposes, in a typical landscape we'll use clouds as

an example of important high values. Nothing looks worse in a

landscape print than a bunch of clouds that are reproduced as blank

paper white. Ideally, clouds in a landscape print should have a full

range of texture and subtlety.

I'll meter the lightest sunlit areas of the clouds with the spotmeter

and see where they fall in relation to my Zone III-IV placement of the

important low values. If they fall at about a Zone VIII, wonderful; I

can just develop the negative normally to reproduce these important

high values in a satisfactory fashion. But, in a typical scene, they

usually won't fall so neatly on the zone scale.

Let's say these clouds typically fall on or about a Zone IX, maybe as

high as a Zone X. This tells me that if I want to be able to retain

these important high values in the final print, and not have them

print as pure paper white, with no subtlety or highlight texture, I'll

have to reduce the negative's development, to compress the tonal

range. To do this I'll give the negative a reduced development time,

N-1 or N-2.

If the important high values fall on a Zone VII, in relation to my

important Zone III-IV low value placement, then I'll have to increase

the negative's development--to expand the tonal range. Constricted

high values in a print will look dull and lifeless. In this case,

I'll give the negative a N+1 development time to expand the high value

placement from Zone VII to a higher Zone.

4. I'll note these measurements in my records, and proceed to make

the initial exposure, as per my meter's indication, for the Zone

III-IV important low value placement. The only change I will make in

my initial exposure will be to slightly (no more than 1/3 to 1/2 stop)

increase or reduce my initial exposure settings.

5. If I anticipate a subsequent N-1 development for the scene, I'll

increase the initial exposure setting slightly, in order to maintain

the low values as initially visualized/placed. If I anticipate a

subsequent N+1 development of the scene, I'll slightly decrease the

initial exposure for the same reasons.

In summary, your initial camera exposure settings may not vary much,

when comparing traditional Zone System practices to an incident light

reading, but the subsequent development given to the negative will

vary a great deal when using the Zone System.

Hope this adds something to the discussion, Sergio.

doremus_scudder1 · June 27, 2000

Pete,

You are making a basic error in assuming that 18% gray is two-and-a-

half stops away from maximum white. The beauty of the Zone System is

that, through manipulation of development times, one can control the

amount of one-stop doublings in the subject (read subject contrast

range) that make it onto the limited usable contrast range of the

negative. I routinely use developments that allow me put a 2 to 6

stop subject contrast range in the area between Zone V and Zone IX in

the final print. Also, I routinely use N-2 to N+2 developments, and

N+3 and N-3 often enough that I have calibrated them thouroughly. It

all boils down to knowing what your film/paper combination will do

and how to expand or contract the subject contrast range so that it

will fit into the limited contrast range necessary on the negative to

make an expressive print.

Regards, :^D)

charlie_strack · June 27, 2000

Pete:

The reference zone is Zone I, the threshold of exposure, not Zone V.

Zone I is really the only density on the H&D curve that has very

little variation with development, thus its use as the primary

reference.

Regarding Zone V being 2.5 zones below 100% reflectance, yes this is

correct, assuming both reflectances are illuminated by the same light.

Recognize also, that 2.5 zones below Zone V is very dark (virtually

black to most people), giving you 5 zones total range. Think about

this: that 5 zone range is the total range you can get from a diffuse

reflecting surface, like a photographic print. This fits my

impression of the range of exposure that easily fits on film and

easily prints.

Where you get a greater range of zones is when different parts of

your subject are illuminated by different light: a landscape with

part in broad daylight, and part in shadow. The eye easily sees

detail in both, but you have to compress this type of subject to fit

it onto the paper. Note: paper not film. As you point out, modern

films easily cover a much greater range of densities/zones, but you

can't print the extreme density range straight onto paper. You are

absolutely correct that the solution is to dodge and burn so that you

compress.

By the way, many modern printing papers have a long toe to

accommodate the lack of a shoulder on these mondern films. End result

is the same, you just do it in a different part of the process.

For contact prints, you also dodge and burn as you need to if your

negative has too great a density range.

As far as choosing a different method other than the zone system, if

it works for you, great. I have a Pentax digital spot meter that I

like. I bought a selenium cell incident light meter a year ago. My

battery went out on my Pentax and I didn't have a spare battery. But

I had a spare meter that doesn't use batteries. They both have their

uses. So does the "sunny 16" rule alluded to in your "idiot guide".

Your message seems like you have a grudge against the zone system. If

you do, it seems pointless. Many of the great photographers in the

early part of the 20th century didn't use meters. What counts is

results. The advantage of studying the zone system, even if you don't

use it, is that it gives you a better technical understanding of

practical sensitometry.

marv5 · June 27, 2000

"I'd be interested to know how much the "expert" exposure deviates

from the idiot-guide on the leaflet included with the film (i.e. June

to September, cloudy-bright - 1/125th at f/8)."

Just to address your last sentence....under those

paramaters....these's not a lot of deviation. The negatives created

in this fashion are very printable, I have printed many 40, 50 or 60

year old negatives and they make beautiful prints. Remember when

the "idiot-guide" was used, it was used for lack of any exposure

meter. The suggested exposure was not arrived at by calculations and

metering, i would guess it was taked from real life situations.

Someone probably went out under those circumtances and exposed film

made notes and arrived at the suggested times. Those times yielded

and still yield properly exposed negatives.

Now we must compensate for an "average" incident meter reading and

adjust the exposure accordingly to create a negative that will be

easily printable. When I use my spot meter, I am adjusting the

exposure to accomplish the same end, create an easily printable

negative. Different roads to the same destination. The Zone System is

just that, a system. It can be very complicated, or as simple as

determining your "key day" exposure as suggested by Fred Picker and

that is in reality just your own personal "idiot-guide".

david_lewis1 · June 27, 2000

Pete:

Your comment about there being 2.5 stops between 18% reflectance mid-

grey and 100% reflectance is correct. However, this does not describe

the full tonal range in the scene. One needs to consider that not all

objects in the scene receive the same illumination. It is the

variance in illumination times the reflectance of each object that

gives rise to the complete tonal range in the scene. Taken together

the intensities of light reaching the film from the various objects

in the scene can cover a very wide band of values - in theory an

unlimited number of zones - but in most daylight scenes the tonal

range will be within a 5-10 zone range.

Dave

john lehman, college alask · June 28, 2000

Dave hits the nail on the head, and also identifies one of the major

differences between outdoor incident and reflective metering. Almost

no flatly illuminated subject has a brightness range of more than

five stops. However, in full sunlight, the difference between a gray

card in full sun and one in full shadow is four stops; with very deep

shade (e.g. heavy woods) the difference can be more than five stops.

Thus, a typical nature scene in full sunlight will have a total

brightness range of 10 stops, even though the subject brightness

range is only 5 stops.

With regard to the question about careful measurement versus sunny

16, it is useful to remember that Ansel Adams developed the zone

system as a teaching tool to explain exposure to students -- most of

his own great photographs were made without it. In fact, once you

are used to a particular environment and film, much of the time

careful measurement with a spot meter or use of an incident meter

with something like Davis's Beyond the Zone System will lead to

exactly the same exposure as no meter and experience. For example,

if it is June in Alaska, a sunny day between 8am and 8pm and I am

shooting a landscape with mountains in the background and forest in

the foreground, I don't need my spot meter to tell me to expose HP5+

with a Wratten 12 filter at f/22 for 1/50 and develop 12 minutes in

PMK. When I was learning, I did need the whole system.

mark_lindsey · June 28, 2000

Of course Ansel used the zone system before he invented it--it is

nothing more than applied sensitometry. Who doesn't do that? (not

counting idiot guide usage).

pete_andrews · June 28, 2000

Thanks for the responses.

To clarify things slightly:

What prompted the question was my own experience in attempting to

apply the zone system to exposure control some years ago. On numerous

occasions then, and since, I've attempted to be "clever" with metering

and exposure control, only to arrive back at more-or-less the same old

exposure value that a simple grey-card or incident reading, or even

the "idiot guide" would have given me.

I've also just been reading a book called "Perfect exposure" which

strongly advocates the zone system, (with zones up to 12!). However, a

lot of the illustrations, while undoubtedly being good pictures, are

admitted to be the result of luck, mistake, guesswork or bracketing.

Adams himself, in "The Negative", frankly admits to getting

unprintably blocked up highlights in at least one example, and having

to resort to dodging and burning in order to print some of his

negatives.

Those respondents who were honest enough to own up to it, have so far

confirmed my suspicion that, in the majority of cases, the application

of complicated methods of exposure determination are largely a

waste of time. Note: I'm not saying the same about control of

the development process, although this raises the moot point of

whether the zone system has any application in colour work, with its

far less flexible processing.

I didn't have any grudge against the zone system when I posted this

question, but some of the patronising responses of its proponents are

making me lean that way. :-) Can I point out: (i) that you don't need

to know anything about the zone system to know something about

sensitometry and densitometry. (ii) that 18% of a pure white reflector

is -2.5 stops (-2.474 stops actually) no matter what development you

give it. (iii) That Adams devotes 3 pages of the section on

exposure in "The Negative" to defining and emphasising the

importance of zone 5 as a reference, and only touches on the use of

zone 1 in the section on development. (iv) that, yes, "pulling"

development does allow a wider range of subject brightness to be

encompassed on a given grade of paper, but micro contrast and acutance

are degraded. (v) that multigrade papers have opened up numerous

possibilities not even dreamed of when the zone system was invented.

(vi) that conventional wisdom should always be challenged from time to

time. (vii) that the use of roman numerals isn't very space efficient.

charlie_strack · June 28, 2000

I'll give my 2 cents on each of your comments.

i) Absolutely true. But if you understand sensitometry and

densitometry, you understand the zone system, albeit in slightly

different terminology.

ii)Of course this is true. But this is luminance, not density.

Processes respond differently to the new materials. And even Saint

Ansel was wrong on occassion. But he made many wonderful photos. So

he is worth paying attention to.

iv) Exactly. See the Film Developing Cookbook, it implies that much

of the earlier Zone System work isn't reliable because tools used at

the time may not have been accurate.

v) Of course.

vi) Always, always, always. This is one of the reasons I appreciated

Fred Picker's writings so much.

vii) True. But in the first Ansel Adam's zone system books he

explained the choice: all of the numbers in common use were Arabic:

ASA, DIN, f/stops, shutter speeds, ft. candles, candels/sq ft. He

wanted to use something that would not be confused with existing

measurements.

I can attest and with you that complicated exposure method are not

very useful. An incident meter or gray card reflected meter will

cover most everything you need. Where spot readings and the zone

system help is in very difficult lighting circumstances. They will

help you get a negative that can be printed, though it may be very

difficult to print.

Then again, the "tip sheet" approach covers 80% of outdoor situations.

steve_swinehart · June 29, 2000

I have a question for you. If you are only using a grey card and/or

an incident reading, how do you decide what development is correct

for your exposure if you don't know the luminance value range of your

subject - especially the area of interest?

As for your "clever metering" problems, I have no idea what that

means. I rarely take more than 3 readings from any subject using a

spot meter. The subject of interest, the darkest area that I want to

retain detail, and the lightest area that I want to retain detail.

That gives me my luminance range of interest, which allows me to set

the exposure, and determine development. All of that takes, at the

most, one minute.

Whether exposure deviates from the "idiot guide" or "sunny 16" rule,

or your incident reading method is immaterial. My question is still -

how do YOU determine development? Choice of developer, and

development time? Or, are those of no consequence?

The Zone System is more than exposure. You can call the method the

Zone System or applied sensitometry - they're one and the same. The

Zone System is only a method to VISUALLY relate the subject, to the

final print. This gives the ability to evaluate exposure and

development choices, and their "predicted" effect on the print prior

to making the exposure.

Conversely, you can make any exposure of a subject, read the density

range on a densitometer, and make a print using the correct paper

grade extrapolated from the density range.

However, that method does not allow you to creatively control the

tonal representations of the subject quite as well. When you start

using filters to alter the look, or exposure to change a flat subject

to high key or low key look, then you need a method in the field to

evaluate the effect of exposure + development on the final print.

Again, whether you formally use the Zone System or just "intuit" the

final results - it's still all sensitometry and you are visualizing

the subject range fitted to the film through exposure; fitted to the

final print though exposure + development.

Or, perhaps, your method is to just point, shoot, and hope for the

best?

As for color work - yes, the Zone System can be applied to color

work - but that's another subject entirely.

pete_andrews · June 30, 2000

To answer Steve's question. If the subject contrast is low or the

lighting is flat, then I'll push the development, but I hardly ever

pull it. It doesn't take a meter reading to see a flat subject or an

overcast day. If the main subject is in shadow then it'll get a run

over with a reflected reading, but I'll also be wary of accepting a

reflected reading from bare rock or stonework because it can reflect

and store massive amounts of infra-red, and all meters, with the

possible exception of Selenium types, are overly sensitive to IR.

These are the sorts of exposure "decisions" I take into account,

almost without thinking about it.

For outdoor subjects you can't get brighter than full sunlight, not

until the sun goes supernova. So my normal development is geared to

giving me an easily printable negative of subjects in full sunlight.

Even clouds have to obey the laws of reflectance, and unless they're

transilluminated they can't be any higher in value than 2.5 stops up

from my incident reading. Nothing short of using a welding visor over

the lens is going to accomodate the full-on glare of the sun. Although

I often use a neutral grad or polariser to control glare, and

sometimes a reflector to soften the shadows of close subjects. These

techniques are directly transferable to rollfilm and colour, messing

about with the development isn't.

Anyway, this didn't start out as an attack on the zone system. It was

merely an enquiry about how far from "the norm" most exposures were,

no matter how many factors were taken into consideration. As a prime

example, take Adams' "Moonrise over Hernandez". He didn't need to know

the luminance of the moon in candles per square foot, just the fact

that the moon is illuminated by the same light source (the sun) as the

earth; and since the moon has no atmosphere, it needs the same

exposure as full sunlight on earth, (EV14 at the equator, about a stop

less for every 45degrees latitude, or in the moons case, elevation).

We end up with our good old friend EV13 (125th at f/8 for 100ISO),

correct it for ASA64, a 3x filter, and use f/32, and bingo! we've got

the same exposure as good ol' Saint Ansel gave.

I was also questioning the value, if you'll pardon the pun, of even

considering zones above 8.

steve_swinehart · June 30, 2000

Rocks and stonework store massive amounts of infrared? Not in the

wavelengths that might influence a light meter.

I worked on a US Army project for nearly 3 years for detecting buried

landmines. My specialty area on that project was the infrared image

processing system. For that system, I used two infrared video

cameras. I used a camera with a response range from 1.5 microns to 6

microns, and one camera with a response range from 8 to 12 microns.

One of the problems was detecting the difference between a surface

laid mine and a rock - many times they are about the same size and

shape. I am here to tell you, that rocks look not much different

than the dirt they are sitting on (thank God) while mines do not. IR

energy is either stored, transmitted, or reflected. However, the

total IR spectrum and the object dictate what is stored, transmitted

or reflected. Stored energy will be in the form of "heat" which will

be above 8 microns and actually more in the 15-40 micron range.

Reflected IR will be in the .8 to 6 micron range. There is no IR in

the 6.2-7.5 micron range because the atmosphere absorbs that

wavelength "notch."

Transmitted IR can go from .8 - 40 microns but it takes special

glasses to transmit IR above 1.2 microns.

While the cells in light meters may be sensitive to IR in the .8 -

1.2 micron range, none of that energy will be stored by the rock,

brick etc. That energy will all be reflected and, as such is

dependant upon the emissivity of the object. Your postulation that

meters will be overly influenced by IR stored in an object is just

not true. And, I would question how much they would be influenced by

reflected IR as my emissivity tests of various objects, including all

types of soil and rocks, show that clay soils reflect more IR than

any rock that I tested.

franki_wango · June 30, 2000

"It doesn't take a meter reading to see a flat subject or an overcast

day."

Some of the highest contrast situations I have photographed have been

on overcast days. Overcast does not necessarily translate to low

contrast. How do you account for a high contrast range on an

overcast day? Do you have "calibrated eyeballs"? I've been fooled

to the point of questioning my meter readings and doing them over

again just to make sure I put the numbers into my notebook correctly.

The opposite situation is, on days with full sun at mid-day have been

some of the lowest contrast situations as the shadows are nearly non-

existant, and the reflected sunlight from sand, rocks etc. has nearly

everything at the same EV. Only the color of the different objects

provides a reflectance range, and in these cases the colors may not

be far apart in reflectance.

"Even clouds have to obey the laws of reflectance, and unless they're

transilluminated they can't be any higher in value than 2.5 stops up

from my incident reading."

I don't know where you photograph, but in the southwest U.S. with

large vistas, it is totally possible to have white areas of clouds

being 4 to 4.5 stops higher than an incident reading. How? You can

be under a cloud shadow for a very large area around you, meaning

everything in your field of view is like shooting on an overcast day,

and if you take an incident reading, that's what it will look like.

While, off in the distance is a huge thunderhead occupying a

signifcant portion of the sky with the top brightly illuminated by

reflected sunlight.

"As a prime example, take Adams' "Moonrise over Hernandez". He didn't

need to know the luminance of the moon in candles per square foot..."

Really untrue. If you read Adams description of making that photo,

it is EXACTLY because he knew the luminance of the moon itself from

other photos that allowed him to setup his camera and make the

exposure before the light changed. If you read his work further, you

will find out it is one of his hardest negatives to print, because he

did not have the time to analyze the total luminance range, carefully

place the exposure, and then alter development to adjust the final

negative tonal range to match the printing paper range. In this

case, it was nearly a point-and-shoot with an 8x10 using a known

value (full moon) placed on Zone VII - and without a full reading of

the scene, he ended up with a difficult negative to print.

"These techniques are directly transferable to rollfilm and colour,

messing about with the development isn't."

Not true. You can "push / pull" color film in the first developer

which does change the contrast.

charlie_strack · June 30, 2000

Re: Rocks "storing" IR.

They don't "store" it, they absorb the radiation. They can then re-

radiate that energy when. But what you are concerned about is the

reflected engergy from your subject, whatever it is. The film won't

capture it, but the meter will. This is why a paid a bunch of money

to have my Pentax digital modified by Zone VI to filter out the IR,

thus reducing the error caused by the IR.

I know the photodiodes and phototransistors detect IR. I've now

worked for 3 firms that manufacture photoelectric sensors. We use

glass lenses, sometimes plastic, and the IR definitely gets through.

We use 880 nm wavelength. Unless you're shooting IR film, a meter

that uses a photodiode and phototransistor sees and measures IR that

the film is not sensitive to, unless the meter filters it out.

Sometimes it's not the theory that is at fault. It's tools that don't

take into account all of the issues they need to.

You can't always be sure of what your eyes see: reads Adam's

Examples. One shot was in France. Ansel felt the light had great

luminosity, but his negatives didn't reflect this. His eyes were

fooled. All of ours can be.

steve_swinehart · June 30, 2000

You are correct Charlie in your statments that the energy is absorbed

and then re-radiated. I used the word "stored" as that is the word

Pete used. IR energy can't be absorbed at 30 microns and re-radiated

at a different wavelength until the object reaches its energy

saturation level. Rocks, bricks etc., don't reach saturation because

there is never enough sunlight energy reaching them AND they are in

contact with other things (like soil or the building structure that

act as "energy sinks" ) to which they constantly transfer energy.

While photodiodes, transistors etc. can be sensitive to IR as can

some types of photocells, trying to predict what objects in a scene -

such as rocks or bricks - MIGHT be reflectors of IR and effect the

exposure reading is impossible as soil itself can often reflect as

much or more IR than rocks.

It is safe to say, that any re-radiated energy will be at a level

that is above the sensitivity of the photocell in a meter as the

energy that is absorbed is above 8 microns - and will be re-radiated

at the same wavelength.

The really big point with any type of object, is that they are either

absorbing OR re-radiating, but not both at the same time. An object

will not re-radiate energy until the energy level incident upon the

surface is lower than the absorbed energy level OR the object reaches

its energy saturation level.

Also, in my experience, the angle of incidence/reflectance from the

sun's direction versus the viewing angle has as much or more bearing

on the amount of IR "glint" as the emissivity of the object itself.

In some of our Army testing, concave depressions in a surface were

not identified as being "mine-like" when running the test vehicle in

one direction, while in the reverse direction they were always

identified as mine-like because of the sun direction / IR reflection.

The solution was to put a 4.2 micron cut-on filter on the 3-5 micron

camera (the platinum silicide sensor was really sensitive from 1.5 -

6 microns). No filter was needed on the 8-12 micron camera because

the greatest percentage of IR energy in that wavelength band is

absorbed and not reflected by soil, gravel, pavement, rocks etc.

The standard solution to IR sensitivity problems with CCD video

cameras is to put IR absorbing glass in front of the sensor. I don't

know what is involved with the Zone VI modifications, but, like a

standard silicon sensor based CCD camera, a thin piece of IR aborbing

glass would be the easiest way keep IR from the meter sensor without

effecting visible light.

The idea that using an incident reading meter with a plastic light

integrating sphere is going to be more accurate than a reflected

light reading with a spotmeter because of IR influence is pure

speculation because, as you pointed out, some IR will be transmitted

through the plastic. And, then we get back to the direction of the

light, reflected IR etc. Basically, it's a specious argument as

either type of meter will be effected unless they have been modified

to exclude IR.

franki_wango · June 30, 2000

Pete -

To answer your question about exposure specifically, I have reviewed

field notebooks from over 30 years of taking photos. There are 57

exposures with -3 exposure (3 stops under incident reading) with

either +2 or +3 development associated with the exposures. There are

122 exposures with -2 exposure with +1, +2, and +3 development. 335

with -1 and either +1 or +2 development.

And then there are lots (the majority of entries) of "normal"

exposures with normal, -1, and -2 development. (I got tired of

counting after the ones above and didn't want to turn this into an

all day project.)

There is probably an amount equal to the minus exposures with plus

exposures and minus development. The plus exposures seem to mostly

be in the +1 range, I would guess there are at least 200, and a like

amount of +1.5 with minus development. I found only about 180 or so

with +2 exposure. And only about 45 with +3 exposure.

So - I guess in my work, there is a total 6 stop deviation from

a "normal" exposure with a lot of different development combinations

(times plus developer types) to compensate for the different total

luminance ranges I've encountered.

Does that help you get an idea of exposure/development deviations

from normal using a spot metered, sensitometry-based exposure

methodology?

pete_andrews · July 3, 2000

Cheeses! This is going off in all directions for no apparent reason.

Firstly, I apologise for a poor choice of wording. Imagine rocks

storing Infra Red! What a ludicrous idea. Though someone who'd

just burned their arse sitting on one at the end of a hot day might

beg to differ. At least no-one has contradicted the fact that most

photometers are overly sensitive to IR. If you don't believe this, try

getting a sensible and consistent meter reading through a tri-colour

blue filter. The piece of thin glass that completely obscures IR has

yet to be invented, and some manufacturers don't even try.

Yes, our eyes can be fooled, but then so can a meter. The underlying

premise of the zone system, and indeed the aim of any creative

photographer, should be pre-visualisation. If we don't have any faith

in the instruments we use for pre-visualising (our eyes and brain)

then we might as well give up. If we can't decide that a scene has

low, or high contrast visually, then how can we decide what tones we

want it to be in the final print? We practise a visual

craft, for goodness sake. We should train our eyes and trust

their judgement. No metering system will tell you which filter to use

and when, and no metering system will turn a poor composition into a

good one.

Franki; the example you give of taking an incident reading under a

cloud is a classic example of using an incident meter incorrectly. The

reading should be taken from the subject position pointing toward the

camera, in the same light as the subject. Obviously this isn't

always possible, but in the example you give, the top of the cloud is

going to be EV15 to 16, if it's in full sunlight, and we can work our

way back from there. If you hadn't stopped reading in indignation when

I mentioned "Moonrise ....", you'd see that I went on to explain

exactly why Adams didn't need to know the luminance of the

moon, and why we don't need to spot meter every sunlit cloud, or every

crest of surf, or the top of every snow covered mountain. The sun is

as constant as, well, the sun. The fact that things come between our

light source and our subject occassionally, just makes this an

interesting studio.

Let's have none of this sensitometrically holier than thou

stuff either. Incident light measurement is based on sound

photometric and sensitometric principles too, since the integrating

hemisphere automatically takes account of light falling into the

shadows of the subject.

charlie_strack · July 6, 2000

Back on track: Here are my specific answers to your original

questions.

Q) A whitewashed wall comes close, for instance, and this isn't even

Zone 8, so where do the higher zones fall? It seems to me that zones

higher than 8 are only of relevance if a source of illumination or

specular reflection is included in the picture, and we are willing to

let objects which should normally appear near-white in the print slip

down the scale to grey.

A) Zones higher than 8 are pure, textureless white to the eye. Let

them show as pure white in the print.

Q) ...but how are these extra zones to be accommodated in the print?

Reduced development and contrast will simply make our prints look

flat. The only answer that I can see in reality is to burn the

highlights and/or dodge the shadows. What do you do with a contact

print?

A)If they are pure white to the eye, and you visualize them as pure

white, print them that way. If you want texture in the print, you're

stuck with dodging and burning. Contact prints are treated exactly as

enlargement (burning and dodging), except they have more inherent

contrast, so burning and dodging are not needed as much. Lenses have

7 main defects: astigmatism, curvature of field, chromatic

abberation, coma, distortion (pincushion, barrel), spherical

abberation, and flare. Flare is the loss of contrast. Use of any lens

reduces contrast, including the enlarging process. Only contact

printing retains the contrast of the negative at the paper.

Q) How many users of the zone system regularly make use of zones more

than plus or minus one stop from the "norm"?

A) I haven't got a clue. I sure don't. And with modern films, more

than +/- one isn't practical with standard developers. You have to

resort to low and high contrast developers.

Q) I'll confess that most of the time I end up exposing within a stop

of what the incident light meter recommends. How about you zone

system users?

A) On the average, my incident meter reads one stop less exposure

than my Zone VI Modified Pentax digital spotmeter. So if we call this

a calibration factor, then mostly they match. Incidentally, my film

speeds test using the modified Zone VI meter usually match the

manufacturer's rating, sometimes 1/3 stop faster. This has been so

predictable for me that I suspect the people who get half-speed are

just compensating for meters that are out of calibration.

Editorial

I am with you on this issue: exposure needn't be complicated. Slight

interpolation of an incident reading or spot metering a couple of

values is all you need for most shots.

james___ · July 8, 2000

Well charli, I guess you've never shot film in the southwest. I get

scenes that have 3 and 4 stops from normal(?). Or in zone parlance, 7

and 8 stop subject brightness ranges. All that tells me is I need

to process in a certain way so I maximize the films ability to

hold detail that can be translated by the paper into as full

tonally full an image as possible. Zone 5 doesn't always mean a great

deal but the subject brightness range means everything. And I do get

negs in the zone 7-12 range and print them like that. Go out to White

Sands NM on a bright day and tell me what your calibrated meter says.

And as far as the zone VI meter it's amazing how many people get such

wonderful full tonal range images without the thing. James

charlie_strack · July 10, 2000

To: James

Allow me to be a bit confused by your post.

Is your point that your subjects have an 8-stop range or a 12-stop

range? Granted there are both. But I'm not sure what you are trying

to say in this regard.

Regarding the Zone VI meter, you can use it or not. It's a tool. A

craftsman gets to choose his tools.

I've got at least 5 different major tools for making holes in my

shop: hand drills, drill press, sabre saw, roto-zip and router. I

choose the best tool for the task at hand. (By the way, if you want

to cut a precision hole for mounting a loudspeaker, the router is the

best tool.)

I've got 3 hand held meters: Zone VI modified digital Pentax, Sekonic

Incident meter, and Polaris flash meter. Each has it's place. You

don't have to have any particular meter to make a fine exposure, or

even a meter at all.

At the time I bought the Zone VI it it elimated some variables that I

know (from my work) are capable of influencing meter readings in a

major way, specifically IR. But my meter is at least 15 years old.

I suspect Pentax has made some modifications in the intervening

years, perhaps incorporating some of the modifications Zone VI does.

This may make the current version less susceptible to these

influences than the earlier ones. But in the end it is only the final

print that counts, and I will be the first to agree with this.

So I am not amazed that many photographers do exceptionally well

without the Zone VI meter. Back to the "idiot guide" or tip sheet, or

sunny-16 rule. For decades most amateurs used these because they are

cheap and, more importantly, they work.

So I have no problem at all with photographers using whatever tool

they choose. I have no axe to grind. But please reciprocate. I find

it a useful tool, so allow me to use it.

And by the way, I have shot film in the southwest, but it's been many

years and long before I knew anything about the zone system or before

I had a clue as to how to make a decent photo. And, by the way, New

Mexico is one of my favorite states, so if you live there, please

enjoy it for me.

pete_andrews · July 11, 2000

James. If your getting readings more than 3 stops above a grey-card,

what you've got is glare. i.e. glancing reflected light, and I

bet you could do just as good a job of controlling it with a

polarizer.

As for zones up to 12! Surely zones are defined by their visual

appearance in the print, not by their luminance in real life? With 10

being defined as pure base white, it's difficult to see how a paper

print can show greater than that. That's the other part of my question

that no-one has really answered yet. What use is assigning zone values

to luminances that can't possibly be accomodated in a print?

jeff_white1 · July 11, 2000

Zones are measures of light during exposure. Tones are shades of gray

in the print. So a zone 12 can be very real but you must do something

in developing or printing to bring it into the range of tones that

the paper is capable of reproducing.

pete_andrews · July 11, 2000

No; EVs, Lux, Lumens per square metre, or candles per square foot are

measures of light during exposure. The whole point of zones is to

previsualise tones in the final print. An 18% mid grey is only

a zone 5 if it's exposed and printed that way. Give it a stop more and

it's a zone 6. Give it 7 stops more and it's a mythical zone 12 which

can never be printed. Yes, you can cut the development to print it as

a zone 10, 9, 8, or even back down to 5, but in doing so the 1 stop

per zone relationship is lost, and the relationship of all the other

tones in the print is devalued, and that makes the end result very

difficult to previsualise. We end up being slaves to a system that

defeats its stated and sole purpose of previsualisation.

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