Is zone system exposure and development manipulations usable with infrared photography?

-- Andre Noble (andrenoble@yahoo.com), January 13, 2002

Answers

Andre,

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?

William

-- William Anderson (katwilphoto@mediaone.net), January 14, 2002.

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)

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

-- Eric Pederson (epederso@darkwing.uoregon.edu), January 14, 2002.

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.

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.

-- Kevin Bourque (skygzr@aol.com), January 14, 2002.

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.

-- Jorge Gasteazoro (jorgegm58@prodigy.net.mx), January 14, 2002.

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

-- Bob Moulton (bobmargaretm@home.com), January 15, 2002.

Hi-

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.

-- Michael Waldron (michael@cadogan.net), January 16, 2002.

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.

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.

Make sure your camera bellows shield against IR, I understand some are "porous" to IR wavelengths.

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?

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

Dave

-- Dave Erb (dberb@aol.com), January 17, 2002.

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.

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.

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.

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.

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

Cheers, Sandy

-- Sandy Sorlien (sand44@mindspring.com), January 19, 2002.

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.

-- Sandy Sorlien (sand44@mindspring.com), January 19, 2002.

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 (james_mickelson@hotmail.com), January 22, 2002.

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.

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.

-- Sandy Sorlien (sand44@mindspring.com), January 23, 2002.