Symptoms
- Top or one side of the image is wider than the other
- Image looks like a trapezoid
- Straight lines appear slanted
- Corners don't line up with the screen
Likely causes
- CommonProjector angled up, down, or to a sideAny tilt relative to the screen creates a keystone (trapezoid) effect.
- CommonKeystone correction turned off or misconfiguredDigital keystone correction compensates for angle but must be set or auto-detected.
- PossibleProjector not centered with the screenBeing off to one side causes horizontal skew even if height is level.
- Less commonScreen or wall not flat/plumbAn uneven surface can distort the projected rectangle.
What to do
- Reposition the projector so its lens is centered and level with the middle of the screen, straight on if possible.
- Use the tilt feet or a mount to level the projector front-to-back and side-to-side.
- Open the menu and enable auto keystone correction if the projector has it.
- If manual, use the keystone sliders to square up the top, bottom, and sides one at a time.
- Recheck focus after keystone correction, since heavy correction can soften the image.
- For a permanent fix, consider a ceiling or shelf mount that keeps the projector centered and level.
Tools and parts
- Level
- Tape measure
When to call a pro
Not typically needed; a mounting professional can help if ceiling installation is required.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.