If you're moving your projector further away then you will get a larger image. If you move it closer, you will get a smaller-sized screen. But this does not mean your image quality stays the same for all distances. This is why it's important to know the minimal and maximum projection distance of your beamer. If you don't have the correct distance, then it may look less bright and less detailed. The text becomes harder to read, and details will be difficult to see.
Make sure to also refocus your projector after you change the position (unless you have auto keystone correction, then it goes automatically). A clear projection image depends on the correct distance, the focus, the resolution and the alignment of the beamer. Keystone correction can adjust your titled projection to be the correct alignment, yet this may slightly reduce image quality. It's important to keep the beamer straight in order to get the best results of image quality; place it straight and centred in front of your screen.
Unfortunately, there is no universal rule that says that one metre always creates a certain number of inches. However, with most mini beamers it's either an ultra-short-throw beamer or a short-throw beamer. But every model has its own throw ratio, which describes the connection between the width of the image and the projection distance.
Use this calculation:
Image width = projection distance ÷ throw ratio
For a 16:9 image, estimate the diagonal screen size with the following:
Screen size in inches = projection distance in metres × 45.2 ÷ throw ratio
45.2 is the conversion factor; it converts the width of a 16:9 image in metres to the diagonal size in inches. This means that a metre wide in 16:9 has a diagonal measurement of about 25.2 inches.
Short-throw beamers have lower throw ratios; they can create a large image from a much shorter distance. This makes it the perfect companion in small rooms. Most mini beamers that you see online are short-throw beamers.
For example, a short-throw beamer with a throw ratio of 0.8 creates approximately the following:
- 0.5 metres: 28-inch image
- 1 metre: 57-inch image
- 1.5 metres: 85-inch image
- 2 metres: 113-inch image
These calculations are estimates, always make sure to check the specifications of your beamer for the accurate throw ratio numbers. The correct projection distance can differ between beamers. The projection distance should normally be measured from the projector lens to the wall or your projection screen. That's the safest way to know for sure.
