How to Determine if Your Pinhole Sun Viewer Is Showing an Image of the Sun

A pinhole sun viewer or pinhole camera is a simple yet effective tool for observing the sun without risking damage to your eyes. To ensure that your pinhole viewer is working correctly, you can perform a few tests. This guide walks you through the steps to determine if your pinhole sun viewer is showing an image of the sun or just letting light shine through.

Testing Your Pinhole Sun Viewer

Follow these steps to test your pinhole sun viewer:

Set Up a Dark Room

Find a dark room and place a bright light source inside. Ensure the room is well-vented and that any possible heat sources are far enough away to avoid creating a fire hazard. Cool LED lights are recommended to minimize any potential risks.

Create a Light Pattern

Cover part of the light source to create a non-round light pattern. For example, you can cut out a circular shape with about a quarter of it removed to create a unique light shape. Carefully place this shape over the light source so that the remaining light forms an distinct pattern such as a comma, ruler, or any other non-round silhouette.

Darken the Room

Move to the opposite side of the room and darken the area except for the light source. Ensure the room remains as dim as possible to allow for the light pattern to be clearly visible.

Test the Pinhole Viewer

Hold your pinhole viewer at a specific distance from a white screen. If the pinhole is the correct size and the distance is accurate, you will see a spot that is not round but rather the shape of the light source flipped. This is the image of the sun. If the pinhole is too large, you will only see a round dot.

The reason this works is that when the pinhole is small enough, the image is in focus and not blurry on the target. If the focus becomes blurry, you will notice the shape becoming rounder. Therefore, it is crucial to test with a light source that has a non-round shape to avoid missing the image altogether.

Preparing for a Solar Eclipse

If your light source can display a non-round shape, it's ready to show you an eclipse of the sun. During an eclipse, the sun's image will be visible with the same non-round shape as your test pattern, providing a fascinating and safe way to observe this celestial event.

A 2017 solar eclipse showcased what the event would look like in San Francisco, and similar patterns can be expected in other regions. This experience not only educates but also provides a memorable and awe-inspiring moment for those who are prepared.

Conclusion

A pinhole sun viewer is an excellent tool for safely observing the sun and experiencing a solar eclipse. By following the steps outlined above, you can ensure that your pinhole viewer is functioning correctly and ready to capture the event. Remember, safety is paramount—never look directly at the sun without proper protection.

Happy observing!