Projectors
What is keystone correction?
Keystone correction straightens the image when the projector is not perfectly square to the wall. Without it, the picture comes out shaped like a trapezoid: wider on one side. It can be manual or automatic, when the projector detects its own tilt and adjusts by itself.
Why the image gets distorted
If the projector points up, down or sideways, light travels farther to one edge than to the other, and that edge gets bigger. The correction compensates for that difference.
Vertical correction fixes an upward or downward tilt. Horizontal correction fixes placement off to one side. Some models also let you adjust each corner separately.
Its one cost
On most projectors the correction is digital: it crops and rescales the image, so fewer of the available pixels are used. With small corrections you can barely tell; at very steep angles the picture loses some sharpness. If you can, place the projector as centered as possible and use the correction for fine tuning.
What to check before you buy
- Automatic correction saves time if you move the projector often.
- Autofocus is a different feature: it adjusts sharpness, not shape.
Products with Keystone correction in our store
This is how it appears on their spec sheet. Open each one to see all its specifications.
Guides to help you choose
Frequently asked questions
No. Keystone corrects the shape of the image; autofocus adjusts its sharpness. Many projectors have both.