Photography is an excellent way to learn the physics of light. Cameras have adjustable settings such as shutter speed, aperture diameter, and ISO speed to modify the way light enters the camera. Black & white photography is monochromatic, consisting of a single color in various shades. The gradient between black and white is produced by color where the chemicals in the film respond to various wavelengths. Photographic filters are used to correct, enhance, or adjust the contrast between the shades. Placed in front of the lens colored filters will absorb different wavelengths of color and alter the way the light hits the film. In this experiment students will explore the properties of light and color by photographing colorful images with and without color filters.
Students will explore the properties of light and color using photographic filters.
- Camera with manual and black & white settings.
- Color filters: red, blue, green, yellow (filters can be purchased to fit specific lenses) or Grafix Clear Lay transparency sheets: red, blue, green, yellow (see bibliography)
- Printer and card stock (paper)
- Create or find an image of the color spectrum and print it on a heavy card stock.
Image from WikiCommons
- In a well-lit room, or outside on a sunny day, set up the camera 3’ to 5’ away, pointing to the color spectrum image. Use a tripod.
- Set the camera output to black & white and place in manual mode.
- Take a photo of the color spectrum. Record the aperture and shutter speeds used. The control will be the image taken without a filter. You should use the same settings when shooting with the filters.
- Place a color filter on the lens. To make a color filter use a color transparency sheet and place it in front of the lens. You an also cut the transparency to the size of the lens casing and secure with tape.
- Take a photo of the color spectrum keeping the field of view and camera settings the same as the control photo. Record which filter is used for each shot using the exposure number.
- Repeat for each of color filter.
- View the images on screen. Did any look too dark or too light?
- Adjust the shutter speed and aperture settings and repeat step 6. Photograph at least 3 sets using a different setting each time. Record all your settings according to exposure number(s).
- View your images on a computer.
- What are the differences between the control and filtered images? What happens to each color on the image when its own color is used as a filter?