How far from the screen should my projector be?

Pick the projector, the screen and where the projector sits, and the calculator gives the distance from the front of the lens to the face of the screen. It uses the same geometry as BenQ's own projector calculator, which is the standard we work to, and the screen sizes SimSpace and GolfBays publish. If a term is new, the glossary has a one-line definition.

Why the height sets the distance, not the width

A projector's picture is always the shape of its chip: 16:9 on the BenQ golf projectors, 16:10 on the Optoma ZW350ST. Most golf screens are squarer than that, 1:1 or 4:3, so if you set the distance to fit the width, the picture only lights about half the height. A 2.8m-wide SIM 2 screen at 0.499 × 2.8 = 1.40m lights 1.58m of its 2.3m height, and the top 70cm of the screen stays dark.

Set the distance so the picture fills the height instead. On the BenQ that means the 16:9 picture is wider than the screen, and the Screen Fill setting blanks the sides so the lit area matches the screen's shape. The spare width lands on the enclosure's black side panels or is blanked, and the whole screen is lit. The calculator does this for you: distance = throw ratio × screen height × chip shape, so the BenQ AH500ST sits 0.499 × 2.3 × 16/9 = 2.04m from a 2.3m-high screen and 2.48m from a 2.8m-high one. If a screen is wider than the projector's picture, the calculator still fills the height, tells you how much of each side stays unlit, and what moving closer to fill the width would cost at the top and bottom.

Where the numbers come from

• BenQ AH500ST: fixed throw ratio of 0.499, projection distance 0.99m to 2.65m, picture offset 112%, so a level projector puts the bottom of the picture 12% of the picture's height above the lens. Screen Fill offers 1:1, 4:3, 16:10 and 16:9.
• BenQ AH700ST and AK700ST: a 1.2× zoom with a throw ratio of 0.69 to 0.83, projection distance 0.92m to 3.67m. For a 2.3m-high screen that is 2.82m to 3.39m, which is behind the ball, so these two suit a ceiling mount, not a floor case.
• Optoma ZW350ST: fixed throw ratio of 0.521 on a 16:10 chip, offset 115%, with 4:3 and 16:9 aspect modes but no 1:1 mode. Optoma does not publish a minimum and maximum distance, so the calculator leaves that line blank for it.

BenQ quotes a 5% optical tolerance on its tables and says to test the real projector before fixing anything, which is why our packages put the projector in a floor case that slides. The BenQ link under the result opens BenQ's calculator with your projector and distance already filled in, so you can check the figure against the maker's own tool.

Floor case, ceiling mount or arm

The three mounts put the lens in different places, and the calculator adjusts for each. Should the projector go on the ceiling or the floor? covers how to choose; this is what each means for the distance.

• Floor case: the lens sits at the calculated distance on the floor, between the mat and the screen. Level, it fills the top of the screen first, so you slide the case back until the top edge of the picture meets the top of the screen, then tilt the last few centimetres with keystone.
• Ceiling mount: the same lens-to-screen distance, overhead. The offset now works downwards from the lens, so under a 2.7m ceiling a 2.3m-high screen needs a small downward tilt and a little keystone.
• Enclosure arm: the arm holds the projector at the front of a 1.5m-deep SimSpace bay, so the lens is fixed at 1.5m. From there the BenQ AH500ST throws a picture 1.69m high on a 2.3m screen, about three-quarters of its height. The calculator shows that so you can decide whether the trade is worth it.

Measured from where

From the front of the lens to the face of the screen, straight down the middle. Add the depth of the projector body and the case or mount when you mark the floor or ceiling: the BenQ AH500ST is 255mm deep and the SimSpace floor case is 58cm long, so the back of the case ends up roughly 0.5m behind the lens position.

Setting it on the day

1. Measure the screen's width and height and enter them, or pick your SimSpace bay.
2. Mark the lens distance on the floor or ceiling, centred on the screen.
3. Set Screen Fill on the projector to the shape the calculator gives, and set the same shape in your simulator software.
4. Switch on, slide or tilt until the picture fills the screen's height, then centre it sideways.
5. Square the last edges with keystone and focus. Only then fix the mount or mark the case position.