Build a camera lens
Build a simple camera lens using magnifying glass lenses, a cardboard tube, and tape to focus and project images safely onto paper or a smartphone.
Step-by-step guide to build a simple camera lens
Step 1
Gather all your materials and put them on a flat workspace so everything is easy to reach.
Step 2
Place a magnifying lens on one end of the cardboard tube and use the pencil to trace its outline so the lens will be centered.
Step 3
Cut out the traced circle from the tube to make a hole for the lens.
Step 4
Cut a strip of black construction paper long enough to line the inside of the tube.
Step 5
Push the black paper into the tube so it lines the inside and covers light-reflective surfaces.
Step 6
Tape the black paper in place inside the tube so it stays smooth and dark.
Step 7
Fit the magnifying lens into the hole so the curved side faces out and the lens sits snugly.
Step 8
Use small pieces of tape or modelling clay to secure the lens around the edges while still allowing it to be slid slightly for focusing.
Step 9
Tape a sheet of white paper onto a flat wall or board to make a projection screen.
Step 10
Point the lens end of the tube at a bright scene through a window or a lamp but do NOT point it at the sun.
Step 11
Move the tube closer to or farther from the white paper until a clear focused image appears on the paper.
Step 12
Trace the projected image onto the white paper with your pencil or have an adult help photograph it.
Step 13
Share your finished camera lens project and a photo or drawing of the projected image on DIY.org
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!
Help!?
What can we use if we don't have a magnifying lens or black construction paper?
If you don't have a magnifying lens use a large reading-glass lens or a plastic toy magnifier, and if you lack black construction paper line the tube with black electrical tape or paint the inside black to reduce reflections.
Why is the projected image blurry or dim and how can we fix it?
If the image is blurry or dim make sure the curved side of the magnifying lens faces out and sits snug and centered in the hole, that the tube interior is smoothly lined and taped with black construction paper to cut reflections, and adjust the tube's distance from the white paper until the image focuses.
How can I adapt this project for different age groups?
For younger kids have an adult pre-cut the circle and pre-line the tube and use a big plastic magnifier and wider cardboard tube for easier handling, while older kids can build a telescoping two-tube focusing system, add an adjustable aperture from black paper, and measure focal length to experiment.
How can we extend or personalize the finished camera lens project?
You can personalize the tube with paint or stickers, add a cardboard tripod or clay mount, fit an adjustable paper aperture or swap lenses of different focal lengths, and photograph or trace the projected image to compare results.
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Facts about optics and lenses
☀️ Safety tip: never point lenses at the Sun — focused sunlight can get hot and damage paper, screens, or eyes.
🔍 A magnifying glass is a simple convex lens that bends light so you can focus a scene onto paper or a phone!
📷 Camera lenses actually flip the scene upside-down on the paper or sensor — cameras (and our brains) correct the image orientation.
🔗 Stacking two magnifying lenses changes the overall focal length and can make the projected image brighter or sharper — experiment safely to discover what works best!
📐 The sharp spot where a lens makes an image is called the focal point — slide the cardboard tube in and out to find and fine-tune focus!
How do I build a simple camera lens projector with a magnifying glass and cardboard tube?
What materials do I need to build a camera lens projector?
What ages is this camera lens project suitable for?
Is this camera lens project safe, and what will my child learn from it?
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