Using
A Gray Card
Do not tip the card up to the light like the
picture on the left. Too much light is seen by the meter
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The middle picture is correct. Position the
card parallel to the front surface of your lens like this.
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Do not tip the card down like the picture on
the right. Less light is seen by the meter.
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Get the camera close enough
so that only the gray card shows in the viewfinder. Once you have the meter reading, back off to frame the view as you like. Be aware that automatic cameras go back to their erroneous ways as soon as the gray card is out of view.
What is a gray card?
Camera light meters
see reflected light, but it is often useful to know the incident light (the
light hitting your subject). With an 18 percent gray card you can get a
reflected light reading which is essentially the same as reading incident
light. Our gray cards are made from mat board. They have been painted to give
results similar to an 18 percent reflectance Kodak gray card. This is
equivalent to zone V. In the zone system, V is the middle tone half way
between black and white.
Why do we use a gray
card?
Here are several
situations that benefit greatly by the use of a gray card to check the
exposure.
These are lighting
situations that fool the typical camera light meter. It never hurts to check
the light reading with a gray card. If you get the same reading with the card
as without, you didn't need it. If the gray card gives a different reading,
you should generally use the gray card recommendation. Or, you could make
several exposures to see which negative comes out best.
Links to other web
sites that explain the use of a gray card
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