Nature Photograhy Expo in Manasas Nov 9-11

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When will your camera's light meter get the exposure wrong! 

The photos below are an experiment to demonstrate how any in-camera light meter (i.e., reflective light meter) can be fooled into under or over exposing a scene If the objects being metered in the scene are not middle grey in tone.

For this experiment I used an old Kodak 18% grey card, and 8 different colored sheets of simple construction paper. The 8 colors were 1) white 2) light brown 3) blue 4) light green 5) orange 6) yellow 7) red 8) black.

The lighting was exactly the same in all of the shots, and I used a Pentax spot meter to get the indicated exposure. (this spot meter is highly accurate and measures the scene with a 1 degree circle). Each colored square has the exposure written along the bottom so you can see the exact exposure used. I kept the aperture constant at f 2.8 so only the shutter speed varies.

The first square is the 18% grey card.   The spot meter indicated an exposure of f2.8 at 1/80 of a second. 

The next 8 shots were all taken at the same exposure - f 2.8 at 1/80 of a second (i.e., the exposure indicated by taking a reading off the Kodak grey card).  All the colors are accurate because we used the exposure obtained by metering off the grey card.  Notice that the white sheet looks white and the black sheet looks black.