Exploring with coloured filters
STEAM EXERCISE
Details:
Ages: 5-99
Time: 10 minutes
Learning Outcome: Notice that when objects in your environment are viewed through different coloured filters, their perceived colours change. Describe how those perceived colours change.
Colour Concept: Coloured filters absorb certain ranges of wavelengths and transmit others. When we look at objects through a coloured filter, the colour of the object can change, because not all wavelengths of light from the object normally reflected by the object when illuminated by white light will be able to reach our eye.
Materials:
Colour Filter paddle set (LINK TO RESOURCES)
Set of coloured objects (like blocks, LEGO pieces, M&M candies, etc.)
White or neutral background
Phone, tablet or Ipad for taking photos
Instructions:
Choose one of the coloured filters from the Colour Paddle set.
Hold it up to your eye and look around your classroom. What do you notice?
Place the set of coloured objects on the white or neutral background. Take a photo.
Hold the filter in front of the camera lens, and take a photo of the same objects. What do you notice? How are the two photos different?
Repeat the exercise with different coloured filters.
Compare the colours you see when the filter is placed close to your eyes and everything you see is filtered, vs. when you place the filter close to an object or picture. Are the colours you see the same?
Figure 1. Colour paddle set
Figure 2. Image through no filter (top left); green filter (top right), magenta filter (bottom left), yellow filter (bottom right).
Vocabulary:
Questions & observations:
How does looking through your coloured filter affect the colours of the objects you see?
How does looking through your filter affect the appearance of white objects?
How does looking through your filter affect the appearance of black objects?
How do the colours you see in the photo, taken with the filtered camera lens, compare to the colours you see with your eye as you look through the filter? Are all the colours the same?
What’s going on?
Coloured filters absorb certain ranges of wavelengths and transmit others. When we look at objects through a coloured filter, the colour of the object can change, because not all wavelengths of light from the object normally reflected when illuminated by white light will be able to reach our eye. This activates your visual system in a different way, and generates a new colour perception.
If the filtered colours when viewed with the eye appear the same as the colours created by filtering the camera lens, then the camera’s sensors and imaging processing mimic the human eye. However, if the filtered colours when viewed with the eye appear different from the colours created by filtering the camera lens, then the camera’s sensors and imaging processing are different from the human eye response. The second situation is the most likely case, as camera systems generally do not reproduce exactly what the human visual system perceives. (See Why is colour appearance device-dependent?)
Find our more:
See discussion on How do coloured filters work?
