Smartphone Projector Calculator
Design your DIY smartphone projector using thin lens equations and optimize distances for sharp images
Calculate Smartphone Projector Setup
Diagonal size of your smartphone screen
Focal length of your magnifying glass or convex lens
Distance from smartphone screen to lens center
Projector Setup Results
Optimization Tips
Thin Lens Equation
1/f = 1/u + 1/v
Variables
- f: Focal length (cm)
- u: Object distance (cm)
- v: Image distance (cm)
Magnification
- M = v/u
- M > 1: Enlarged
- M < 1: Reduced
- M < 0: Inverted
Image Size
- Image Size = |M| × Object Size
- Larger magnification = Bigger image
- Always inverted in projectors
Common Lens Focal Lengths
Required Materials
Setup Tips
Object distance must be greater than focal length
Image will always appear inverted - rotate phone 180°
Set phone to maximum brightness
Use in a dark room for best visibility
Keep phone plugged in during use
Building Your DIY Smartphone Projector
How It Works
A smartphone projector uses a convex lens to project an enlarged image of your phone's screen onto a wall. The thin lens equation determines the optimal distances for sharp focus and desired magnification.
Key Physics Principles
- •Convex lenses converge light rays to form real images
- •Object must be placed beyond the focal point
- •Real images are always inverted
- •Magnification depends on distance ratios
Construction Steps
- 1Cut a circular hole in the short side of a shoebox to fit your lens
- 2Secure the lens in the hole with hot glue or tape
- 3Create a phone stand inside the box using cardboard
- 4Paint the interior black to reduce light reflection
- 5Use this calculator to find optimal positioning
Pro Tip: Take measurements of a working setup to calculate your lens's focal length for future projects!
Setup and Usage Guide
Prepare Environment
Set phone to maximum brightness, lock rotation to landscape, and dim room lights for optimal viewing.
Position Setup
Place phone and projector at calculated distances. Fine-tune positioning for sharp focus on the wall.
Optimize Image
Adjust projector distance from wall to achieve desired image size. Use apps to flip content if needed.