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Projectors promise true home cinema. So that it doesn’t feel like row 1 in the cinema – including a stiff neck – and you find the right projector, you need to know what a projection ratio is and how to calculate the ideal value for your projector:

What exactly is the projection ratio?

The projection ratio, also known as “Throw Distance”, indicates how far a projector must be from a wall or screen to project a 1 meter wide image. Samsung The Freestyle or Xgimi devices Halo+ and Elfin indicate 1.8:1 here – so they need a distance of 1.80 m to project a width of 1 meter.

Laser TV from LG.
Laser TVs have been on the market since 2013 – but only now are they booming. (Photo: LG)

Short-throw projectors – also called laser TVs – often have a ratio of 0.4:1. So you project a width of 1 meter with only 40 cm distance from the wall/screen.

Placing your projector further away from the wall/screen will also make the image bigger. Here the projection ratio behaves linearly. A 1.8:1 projector placed 3.60 m from the screen will have a width of 2 m. At a distance of 5.40 meters it would theoretically be 3 meters wide, etc.

Calculation: Image Width = Distance / Projection Ratio

The different projector categories are sorted by projection ratio. The respective value means:

  • under 0.5: (Ultra) short throw projectors are the only option here
  • between 0.51 and 1: Short-throw projectors are the favorite projectors here
  • between 1.01 and 1.5: Short and normal range projectors deliver the corresponding image
  • more than 1.5: Only normal distance projectors can be used here

Calculate the ideal projection ratio

Most people want to take a different path. A space has been made available for the screen, so it is also known how large the maximum projected image width is and where the projector should be placed.

To calculate the correct projection ratio, simply rearrange the above formula:

Projection ratio = Distance / Imagewide

For example, if an image width of 3 m is possible and the projector is 4 m away, the ideal projection ratio is 1.33:1.

Fixed ratio projector

As simple as it is so far, there are a few technical subtleties to be noted between the projectors. Let’s stick with the above example: Finding a projector with a projection ratio of 1.33:1 is quite difficult.

Especially in the entry-level segment, many projectors offer a fixed projection ratio, usually between 1.8:1 and 2.1:1. That means you place these projectors at a certain distance shouldif you want to tease the maximum in image width.

However, there is a trick that manufacturers use to more flexibly adjust the image to your existing screen: digital zoom. With this setting you “reduce” the image to the canvas size.

This is practical so that the projector projects the moving picture content accurately. However, this means that there is a white frame around this photo, as the light casts the light through the lens on the wall in a dull manner despite the adjusted rendering.

Digital zoom on the Xgimi Halo+.
Great example of digital zoom. The game (framed in red) is aligned correctly. Without alignment, the projector would fill the green-framed area, interfering with gaming pleasure.

You may notice this phenomenon with the automatic keystone correction, which Xgimi, Samsung and Co. use often.

Here the projector adjusts the projection so that it appears exactly square and balanced on the screen. A clear frame is still recognizable.

The only thing that helps with this is to align the projector as centrally as possible to the screen and at a 90-degree angle.

Projector with variable projection ratio

If you want to set up the projector more flexibly, we recommend a projector with a variable projection ratio. This allows you to fine-tune the projection ratio. Information on the projection ratio can be found on the product pages and in the manufacturer’s data sheets.

Projector with variable projection ratio
At you will also find the projection ratio of the projectors in the product details.

Usually open this is also indicated on a projector with a variable projection ratio. This will help you with the purchase decision.

The advantages of this technology have been mentioned, but the disadvantages cannot be completely ruled out. Projectors with a variable projection ratio show more distortion at the edge of the image, so that the colors there are often alienated and somewhat blurry.

What the projection ratio hides

The projection ratio determines the image width – but says nothing about the actual projection quality. Three other cards are important here.

The lumen specification tells you whether the projector is completely suitable for daylight or only works in darkened rooms. Elsewhere, we’ve covered the subject of brightness in more detail.

In general, the closer the projector is to the screen, the brighter the projected image. Laser TVs combine short distances with accurate image projection and maximum brightness.

The further away the projector is, the darker the image appears because the same amount of light has to fill a larger area.

In addition, the resolution is an essential factor for home cinema enjoyment. Inexpensive entry-level projectors rely on video output below 1080p, often even the 480p common for DVDs at the time. Only coarse-grained mud ends up on the big screen.

At least 1080p makes sense, in some cases also a 4K output, even if this is done via the cheaper pixel shift.

And finally, the screen also determines the overall visual impression. Cheap fabric canvases for under $20 are preferable to wood chip wallpaper, but they outshine light areas.

The respective manufacturers offer alternatives whose high-quality screen fabric “swallows” and reflects the projected light differently.

Head: / Adrien Olichon

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