Grab the 18% Gray Card, white paper and black paper that you used in the previous test. This time you’ll use your incident meter to get a reading.
Put your camera on a tripod, place the gray card in your scene so it fills the viewfinder and then light it evenly.
Put your camera into Manual exposure mode. Set your light meter’s ISO and shutter speed.
Place the light meter on top of the gray card, with the white dome pointing directly at the camera. Make sure you aren’t casting a shadow onto the gray card. Click the “Measure” button.
Set the camera’s F-stop to the value from the meter and take a photo.
Replace the gray card with the white paper. Again, take a reading and notice that it’s exactly the same reading as it was with the gray card. Take a photo.
Replace the white paper with the black paper. Again, take a reading and notice that it’s exactly the same reading as it was with both the gray card and the white paper. Take a photo.
Compare all three photos. You should have a gray image, a white image and a black image.
This time you know the deal, so you shouldn’t be mystified or amazed.