Model No. OS-9498
Pinhole Viewer
5
®
Activity 2:
Examining the Relationship between Pinhole Size and Image
Focus
Note: This activity must be performed in a dark room.
Procedure
1.
Set up the apparatus as instructed in the "Equipment Setup" section.
2.
Turn on the incandescent bulb. Turn off the room lights.
3.
Hold the Pinhole Viewer parallel to the tabletop. Observe the image of the bulb through the
Pinhole Viewer. Notice the quality of the image. In the table, record the focus level for the
small pinhole size. Use the following scale to determine the image quality: 1 = very blurry
(no discernible shape), 3 = some blur (can see lines and circle, but appear fuzzy), and 5 =
excellent focus (lines very clear and good contrast).
4.
With a push pin, triple the size of the pinhole. Record the focus level for the medium pinhole
size. Keep the Viewer the same distance from the bulb as in step 3.
5.
Increase the pinhole to the size of a pencil. Record the focus level for the large pinhole size.
Keep the Viewer the same distance from the bulb for each measurement.
Analysis
1.
Describe the relationship between pinhole size and image quality (focus level).
2.
Draw a ray diagram for each pinhole size to support your reasoning.
Equipment Required
Part Number
Pinhole Viewer assembled
OS-9498
Incandescent light bulb or equivalent
Push-pin
Pinhole Size
Focus Level (1-3)
Small
Medium
Large
