Photo Safaris - Exposing White Right



				John Shaw Nature & Digital Photography Workshops Click here for locations and dates
				Mexico's Colonial Heartland March 17–24, 2007
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				Masai Mara Wildlife Reserve, Kenya September 7–21, 2007
				Australia Wildlife November 1–20, 2007

On my last two photo safaris we encountered situations where our photo subjects included large expanses of snow. I was immediately deluged with questions about making correct exposures. After rather lengthy conversations I realized that photographing predominantly white landscapes is still a mystery to many tour participants. Lets go over what camera meters do, and discuss how to deal with "white subject" exposure problems.

Meters do not tell you the aperture/shutter speed values to use for correct exposure. Let me define "correct exposure." It means getting a slide back with your subject rendered as you wanted it to appear. If you want the medium blue sky to record as a medium blue, and indeed it is that tone on the film, then youve made a correct exposure. If you want the white snow to record as white, and it has, then youve made a correct exposure. If you want to leave the lens cap on while you take a picture, and you have, then youve made a correct exposure. "Correct exposure" has nothing to do directly with the meter reading values; it has all to do with your choices in making the picture.


	Yellowstone frost fog: I metered the brightest white area, about 1/3 way up the right hand side of the frame, then opened up 2 1/3 stops.

Most current cameras offer a choice of three metering modes: a spot meter (which reads a very small section of the frame), a center-weighted meter (which reads the central portion) and a matrix or evaluative meter (which divides the frame into many small sections and evaluates them). These three choices are available in both the manually set exposure mode (where you actually set both shutter speed and aperture) and all the auto-exposure modes (aperture priority, shutter priority and program), and are independent of AF or manual focus.

When you use the spot or center-weighted patterns, the meter tells you what shutter speed/aperture settings to use IF you want to render the subject youre pointing the meter at as a medium tone. This is not always true for "matrix" or "evaluative" metering patterns in current Nikon and Canon cameras. These metering modes run a software program to arrive at a final exposure value; they are biasing the suggested exposures according to their programs.

So lets go out and meter something. If youre working on average-toned subjects you should have no problems. Most things are average tonality, neither light nor dark in tonality. Point your camera at the subject, take a meter reading and press the shutter.

But along comes a white subject, such as a snowy scene, and now you have a problem. The absolutely worst thing you can do, in terms of exposure with slide film, is to burn out the highlights. Think about this: in our everyday lives we are used to seeing blocked-up black shadow areas with no visible detail in them. But we rarely encounter burned-out blank highlights completely devoid of detail. Thats our experience of life, so we need to record some detail in the whites on our film.

If you simply point your camera at the white area, meter using either the spot or center-weighted patterns, and shoot at the suggested exposure values the whites will, of course, be rendered as a medium tone. You have to add some light to the suggested exposure.


	White Sands National Monument, rabbitbrush in autumn: White Sands is one of my favorite locations, but one where precise metering is mandatory. Here I metered the brightest white in the frame, just below the furthest left section of rabbitbrush, then opened 2 stops from my spot meter reading.

What about the "matrix" and "evaluative" patterns touted by the camera manufacturers? If you meter a white area using one of these patterns, will the results record as white? Will the software programs recognize an entirely white scene and expose it as such? Lets try it. Set your camera to the manual exposure mode and meter a sheet of white paper (fill the frame with the paper) using the spot-metering pattern. Center your meter display to the zero point, and you know that the film would record the white paper as a medium gray. Now, without changing anything else, switch your camera to the center-weighted metering pattern. The finder display should still read out at the "zero" position. Once again dont change anything else, but now select the matrix/evaluative metering pattern. What happened to the suggested exposure values? Did they change? I tried this test using a Nikon F5, a Nikon F100, and a Canon EOS1n. All read out the exact same exposure values as did the spot and center-weighted patterns. Matrix programs do bias the exposure if you have a range of tones within your scene, but apparently do not if youre metering only white.

So, if none of these metering patterns will render a white subject as white, then what do you do? You have to open up to allow more light to hit the film. But here comes the big question: how much do you need to open up from the base reading?


	Torres del Paine: Here's a very contrasty scene. The wind was extreme, with the sky/cloud patterns ever-changing. The one constant was the lenticular cloud just above the middle peaks. I spot metered it and opened up 2 full stops.

All color slide films can hold detail in a range of roughly five stops. From a medium placement (the meter reading, that is) one stop open gives you a "light" tone. This is the tone of dry sand, the palm of your hand, white bread lightly toasted, or beige file cabinets. Two stops open yields pure white, but still with detail. Two and a half stops open renders the subject as detail-less white. FYI, this last is exactly the tonality of the white side of a Kodak gray card. According to Kodak it has 90% reflectance. Remember that stops are doubles and halves. If 18% reflectance is medium, then 36% is one stop lighter, 72% two stops lighter, and 144% (if there were such a reflectance) three stops. In a geometric progression, 90% is half way in between these last two values.

So just how white do you want your white subject to be? For example, we speak of snow as "white" but its really all sorts of tones, depending on whether its in shadow or bright sunlight. So heres the answer: choose one specific area of your scene (I would pick the brightest "white" area, since you want to hold detail there), spot meter it and only it, then place that particular area as the tonality you want it to record by opening up accordingly. Read that sentence again as its the sure answer to exposing for whites. I would strongly suggest that you use spot-metering — so you dont accidentally meter adjoining areas — and in the manual exposure mode — since what you set is what you get without the necessity of holding down exposure lock buttons. Meter the bright area, decide how white you want it to be and open up accordingly.

Ive heard it suggested that to hold detail in whites you should only open up one stop. As I mentioned, this is roughly the tonality of white bread lightly toasted. OK, is your "white" subject lighter or darker than that slice of toast? If its lighter and Ill bet it is then you must open up even more. Dont worry; youll still have detail in that subject.

I think you need to open up at least 1 2/3 stops to record white as white. I would go all the way to two stops open for a bright white. By the way, if youre photographing a snow scene on an overcast, day youll need to open up even more. In this lighting situation there is no detail in the snow surface at all, since it is the shadows caused by direct sun that give that sparkling effect. On an overcast day the snow is a detail-less white to your eye, so meter it and open 2 1/3 to 2 1/2 stops. Jack Dykinga, who I think is the best


	Polar bear: I metered the bear and opened up 1 stop. I checked my exposure by metering the ice just below the bear's front feet and placing it 1 1/2 stops open.

4x5 landscape photographer around, states the following in his new book Large Format Nature Photography (Amphoto, 2001): "You can meter off white areas [note: Jack uses a spot meter] and open up your lens from 1.6 to 2.3 stops, depending on how white you want your whites to be. For example, in shooting snow scenes I meter the snow in soft overcast light and open the lens 2 stops if I want the snow slightly bluish or 2.3 stops for pure white snow."

Look at my photo of a polar bear, taken on the 2001 Svalbard trip. Polar bears are not white; they are cream colored, about one stop lighter than medium. But the snow is lighter than the bear. If you metered the snow and opened up only one stop, what tonality would the bear appear to be? Roughly a medium tone, that is a middle-tone gray; but polar bears are not average in any way. To properly expose the scene either meter the bear and open one stop or meter the snow and open two stops. Both methods will give you the same exact answer in terms of the actual shutter speed/aperture combination.

I would urge you not to use an incident meter when youre photographing white subjects or working snow scenics. An incident meter measures the light falling on the subject, and gives you the same answer as metering a gray card would. But this does not work well when your subject is predominantly at one end or the other of the tonal scale. Think about this: the old "sunny f/16" estimated exposure rule, the same as an incident reading in bright sunlight, works for medium-toned subjects but not for white or black subjects. For both of these you must add or subtract a stop of light.

The best way to work white subjects is to spot meter a specific area, decide just how white you want that particular area to be, then open up accordingly. To sum up, here are my suggestions:

1. Set your camera to the spot-metering pattern in the manual exposure mode.

2. Meter the brightest "white" area and only this area.

3. Open up a minimum 1 1/2 or 1 2/3 stops.

4. On overcast days, open up 2 to 2 1/2 stops.



	Joseph Van Os Photo Safaris, Inc. P.O. Box 655, Vashon Island, Washington USA 98070 Phone: (206) 463-5383 Fax: (206) 463-5484 Email: info@photosafaris.com Copyright © 2008, Joseph Van Os Photo Safaris, Inc.