ACE Camera Photography Magazine

The Tool for Better Exposures
Using 18% Gray Cards, cont.

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A gray card can solve difficult exposures. First, it can take the place of an expensive incident light meter, giving you an incident light reading with your camera light meter.

Have your subject hold the gray card straight up and down aimed at the camera. When photographing an object, rest your gray card against it or hold the gray card in one hand. Take your light meter reading and adjust the camera settings with your free hand.

Fotowand 18% gray card Have your subject hold
the gray card. Put your
camera on manual, fill
the viewfinder with the
gray card and take your
light meter reading.

The important things to remember are:
Both the gray card and the subject must be receiving the same illumination.
Completely fill your viewfinder with the gray target and exclude everything else. If you are using a zoom lens, zoom in to get your light meter reading, set the exposure, then zoom back out to the scene you want to photograph.
Don't cast your shadow in the light path falling on the gray card otherwise you'll get a false reading.
Your camera must be on manual mode or able to hold a light meter reading until you press the shutter. (If your camera is set on automatic, the light meter reading will change immediately after you pull back from the gray card and you'll have wasted your time.)

Sometimes sunlight comes from the side. In this situation, hold the gray card straight up and down, halfway between the sun and your camera position. Take your meter reading from the card.

When using artificial light indoors, hold the gray card halfway between the main light source and the camera position.

hold gray card halfway between light source and camera position When light comes from
the side, hold the gray
card halfway between
the light source and
the camera position.

Exposure Adjustments?
The gray cards illustrating this article are the distinctive polystyrene products of Fotowand Technic. Besides being extremely durable they have an advantage over cardboard gray cards. Fotowand's gray cards don't require any exposure adjustments with sidelighting because the surface is dead matte and has a micro-prismatic surface. Light from angles up to 45 degrees is reflected everywhere at the same intensity.

If you use a generic cardboard gray card or an incident light meter in strong sidelighting and other tricky lighting situations you may need to make exposure adjustments for pleasing results.

One tip especially for snow photography
If you don't have a gray card handy, you'll get much better pictures if you put your camera on manual and take a light meter reading from someone's medium gray or brown parka. Continue using this same exposure setting until the light changes.

A reference value for color balance
Shooting a gray card on a frame of color film gives a professional photo lab a standard reference value for color correction. This is especially useful for photographers doing a job where the print must match the original, as in fashion and product photography.

Fine tuning darkroom techniques
Including a gray card negative on a roll of black and white film helps a home darkroom enthusiast make adjustments in his light metering, film processing and printing techniques.

More Uses for Gray Cards

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Published February 17, 2000