This is a lesson I use with my photography students. But it is also useful for helping students understand values.
I tell my students that we are going to trick our cameras. We set up a still life with several black objects, several white objects, and several middle grey objects. Here, I have a mug, a spoon, and a piece of fabric in each value.
We set our cameras on auto and shoot all the objects together with the flash turned on and also turned off. Then, we use the manual mode and let the camera meter tell us the exposure to use, without a flash. A tripod may help. In this picture, we have all the objects assembled together and photographed without a flash at the camera's recommended exposure. Everything looks good.
Then we follow the same procedure with a set up of all the white objects. It is essential to crop in so the objects fill the frame. In the picture below, we have all the white objects assembled together and we have photographed them with several different settings until have a picture in which everything looks grey, not white.
Then we follow the same procedure with a set up of all the black objects. In this picture, we have all the black objects assembled together and the mug is now brown while the spoon and fabric are now grey. In fact, all three of these pictures portray the fabric at about the same middle grey value, no matter how we compensate psychologically.
Many of my lesson plans are designed to surprise the student--to let them make a discovery. This is one of those lessons.
The result of this exercise is normally three photos of grey objects. The white objects are underexposed and become grey in the photo. The black objects are overexposed and become grey as well. The grey ones remain grey.
The camera meters for an average middle grey. That's why the setup with all the objects evenly distributed turns out just right, but the photos of individual objects all turn to greys.
When I last did this lesson, Nikon cameras set on auto generally did well with whites. But when shooting manual and trusting the meter, you can trick the Nikons, too.
