Zone Sytem & B&W Infrared Photography

Andre,

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I think that the zone system *can* be used in infrared. My thought is

how? Where would we find a meter that would be sensitive to the

spectral range of IR film and processing. Night vision goggles

anyone?

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William

In my limited experience (only about 20-30 sheets of Maco 820c) you

can do "zone educated guessing". IR light in typical scenes is more

contrasty than visible light (e.g. foliage is highly reflective,

lumber very dark). However, most of the time, the photographer using

IR film wants fairly dramatic contrast, so that need not be

compensated for very much. IR light is more contrasty when visible

light is more contrasty (direct sun and deep shadows), so assuming

you have a set amount of contrast in mind, you can guesstimate N+1, N-

1 etc. from the visible light reading. Since your can't be certain of

your base exposure either, this is obviously a bit variable. You

couldn't do proper calibration without IR metering (some meters might

allow this if you could filter them and knew their IR sensitivity

relative to the film). I've done a terrible job on the exposure with

many photographs. Fortunately, the "IR-effect" combines very well

with blown-out hightlight, etc., so negatives which would seen

unprintable with regular film are surprisingly workable when shooting

IR photography (this is more true in LF than in smaller formats since

there is always some silver exposed in the shadows on a large

negative). In fact, I only shoot IR film in LF now. Unfortunately, I

keep scratching the Maco film (more like handling TechPan than TMax)

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Then there is season, latitude, and solar time to compensate for...

I seem to recall a magazine article by a fellow who had built a

portable infrared viewer so he could see things like his film did.

He claimed it took much of the guesswork out of IR photography. I've

completely forgotten the details (and where I saw the article), but

maybe someone else out there remembers it.

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Even without the viewer, you can still compress/expand by varying

development time. But, as someone else pointed out, exposure is

still a shot in the dark, so to speak.

I once saw an article, I think on View Camera, where the author built

an infrared meter. As you know the only limitation with the zone

system and infrared is that you dont really know how much radiation

is falling on the film, with the meter you would be able to know and

test.

Laurie White has an excellent text on the use of infrared film. Her

text stresses 35mm and kodak HIE, but I believe thje background data

and her explanation of the dynamic range of the film would help you.

Bob

Hi-

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I have the Pentax digital spot meter. It clearly is IR sensitive,

becuase when I put the #87 opaque filter in front, I still get

readings which are correlated to illumination. Using Maco, I also got

accurate exposures that way. Of course, it is tricky to aim the

meter, then keep it there while putting the filter in front, etc., but

it did work. I did not try calibrating the film to N+1 etc. I assume

that it would respond in some manner like normal film.

RE: an above response, I think the articles on the Infra-Red viewer,

and meter alterations for IR, were published in Phototechniques

within the last 10-12 issues. Also see a book by Theresa Airey about

IR films, though she talks mostly about 35mm and 120 IR films.

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From my limited experience with LF IR films (Kodak HIE and Maco),

getting a printable negative is no small trick and a Zone System

calibration process would be hard work. Longer exposure times (i.e.

1/4-2 secs, with stopped down aperture for improved negative

sharpness, and adjustments for bellows extensions) can be tricky and

have led to fogged or badly overexposed negatives, I don't know

which. I enjoy using IR films for an offbeat rendition of an

otherwise "straight" landscape and appreciate the uncertainty it

interjects against my Zone System exposures with TMX.

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Make sure your camera bellows shield against IR, I understand some

are "porous" to IR wavelengths.

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Wonder if any old photogrammetry books would have a discussion on

exposure for Kodak's IR aerial photo film, at least as the basis for

discussion?

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Good luck and keep us informed if you do try testing.

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Dave

I haven't used the Maco (or any sheet IR film) but did use the Kodak

HIE (high speed infrared) 35mm film exclusively for over 15 years. I'm

not a scientist, but in practice I think it is a mistake to think of

this film as inherently high contrast. It is actually rather low

contrast because IR radiation produces greater shadow detail, and it

tends to scatter around everywhere. As with visible light, contrast is

first and foremost a function of the lighting of the original scene.

So, panchromatic or IR films will make high contrast images in the

desert on a sunny day, and low contrast ones in the swamp on a cloudy

day.

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The reason IR film is thought of as high contrast is because of the

common use of red filtration to jack up the IR effects (by blocking

some of the visible light). Red filtration will also increase the

contrast of panchromatic film, by the way. Your blue skies go black,

and the high IR reflectance of sunlit foliage is accentuated. You do

get great density on your negatives in those highlight areas, and

extreme lack of density in those blue skies and blue water. But this

happens much less with a yellow filter (which I use) or on a cloudy

day with any filter.

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I process all my IR film in D-76 at 11 minutes as Kodak used to

recommend. Now they have changed it to 8 minutes. I called them from a

workshop I was teaching to ask about that, and they said that the way

most people use it, 11 minutes made the negs too contrasty.

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The way I use it, I need the 11 minute development to be able to print

on #3 paper. So for me it does not act like a high contrast film. Note

that I do tend to work in winter light with a yellow filter, for

relatively subtle effects, while most people do not.

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I would take all of these variables into account based on how you

work.

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Cheers, Sandy

To add to my comment, and Eric's about compensation, you must also

compensate for altitude. There is less IR radiation in the mountains

as there is more UV. At 5000 feet I would add a stop of exposure.

Film does not see ultraviolet light. Blue light yes of which there is

more at higher elevations due to decreased water vapor and atmosphere

but there is allso a corresponding increase in IR. The sun is a

prodigous producer of IR light. There is not much water vapor and

atmosphere at higher elevations to bounce IR light into the shadows

and that is the reason that there is a corresponding increase in

contrast at higher elevations. To use a meter effectively using IR

film, you meter the shadows and use the requisite filter factor you

would normally use. You can use the red filter with assurances it will

still function adequately enough to measure the shadows correctly. I

place my desired shadows on zone 4 and find out what the contrast

range is in the scene. This is where it is a guessing game which can

become easily understood with a little experience. You don't need to

bracket as much as shoot 4 sheets of film and bracket the development

of the film by underdeveloping it 30% then 10% then plus 10% and

finding out which development scheme is right for the 4th sheet. You

can see some examples of IR work at usefilm.com/members

utilities/members list/mickelson. IR is very easy once you use it

some. Of course you need to use real IR sensitive film. And only

Kodak High Speed Infrared Film is real IR film. The others are poor

imitations. I've still got 5 boxes left. James

James,

Kodak's "Applied Infrared Photography" shows a chart with indicates

that panchromatic and IR films are both sensitive to ultraviolet light

(below 400 nanometers). Yes, it does show up as blue on color films,

that's why you'd use a UV filter. For B&W it's a non-factor.

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Regarding altitude, in my experience there is less IR at altitude. I'm

not sure why, though, since you are right about the sun being the

strongest source of IR. It's best for anyone working at altitude to

run tests.

Hi,

I've been searching though some old postings and came across this thread. I've got the answer to your light meter question. At my website http://www.davidromano.com you will find an infrared light meter that you can use for a Zone system level of exposure control. I'm not joking around. This is the real thing.

David