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# Size and Brightness of Projections

We're often asked 'how big' and 'how bright' a projection will be. Size is easy to explain but brightness isn't so easy. Here's some information to help you...

## How big will my projection be?

The size of a projected image depends upon two things: the focal length of your lens and the distance between the projector and the projection surface (e.g. a wall). OPTI projectors come as standard with an 85mm lens but 60mm and 100mm option are also offered. The 60mm lens gives a slightly wider projection than the standard type while the 100mm lens gives a narrower projection.

If you move a projector further away from the surface you're projecting onto, the diameter of the projected image will increase. The following table gives a rough idea of projection sizes with each type of lens at various distances. Please note that this is just a rough guide - sizes are very approximate.
Distance/Throw60mm Lens85mm Lens100mm Lens
1m0.64m0.49m0.39m
2m1.29m0.95m0.78m
3m1.94m1.40m1.17m
4m2.59m1.85m1.56m
5m3.24m2.31m1.95m
6m3.90m2.77m2.34m
7m4.55m3.22m2.73m
8m5.20m3.68m3.12m
9m5.86m4.13m3.51m
10m6.50m4.59m3.90m
11m7.15m5.05m4.29m
12m7.80m5.50m4.68m

The above shows that a projector positioned 3m from a wall will result in a projection approximately 2m in diameter when using a 60mm lens. The projection would be approximately 1.4m wide with an 85mm lens and approximately 1.17m wide with a 100mm lens.

The size of a projection also depends upon 'object size'. This is the size of the artwork or pattern on your effect or projection slide. Effect Cassettes result in a very slightly smaller projection compared to image/liquid wheels, but the difference is small. The above give approximate sizes for both.

See our range of lenses here.

## How bright will my projection be?

This is a hard question to answer! Projection brightness and effectiveness depend upon several factors including:

• how powerful the projector is
• size of the projection (see above)
• type of effect being used
• amount of ambient light in the room
• colour/texture of the projection surface

Each of these factors is explained below, but generally effects projectors are intended for use in darkened rooms and the effectiveness of the projection becomes quite weak if the projection size is too large. Generally projections up to 5m across are OK for an OPTI Solar projector in a darkened room.

### Projector power

Naturally a more powerful projector will give you a brighter and more effective projection. The Solar 250 LED is the most popular choice and the most powerful of the Solar range. It has arond the same output power as the original halogen lamp based Solar 250 projector and is suitable for projections up to around 5m in diameter in a reasonably dark room. Larger projections are very possible but it does depend heavily on the amount of ambient light in the room and the effect used.

### Size of projection

Naturally the effectiveness of a projection becomes lower as the projection size is increased because the available light is spread over a bigger area. Projections in a smokey room (e.g. if a fog machine is used) will also be weaker over longer distances because the light hits the fog particles and less reaches the projection surface.

### Type of effect used

The depth of colours in an effect wheel, cassette or photographic slide strongly affect the brightness of a projection. Deep colours will appear less bright. The most striking effects with highest contrast are black and white.

### Amount of ambient light

For best results minimise the amount of other light in the room. Projections in daylight or brightly lit rooms are very ineffecive unless you have a very powerful projector. If you must have other light sources, angle them away from the projection surface.

### Colour/texture of projection surface

The whiter/brighter your projection surface the better. A slight colour to a wall may result in less effective projections. Dark colours will not be effective. Often experimentation is best to find the best surface and sometimes hanging meterial over a wall gives the best effect. Very creative projections are possible by projecting onto stretched lycra fabric.