3. How big can your image be?
A big screen is what projectors are all about. But while your projector might be able to project an image anything from 3 to 10 feet in width (or more with some models), you need to consider the size of the projector screen that you're going to project your image onto.
A two-piece performance
For a quality home-theatre experience, a projector needs to project its image onto a dedicated projector screen. A blank wall, no matter how white, just doesn't work. The paint texture shows through, the light reflections can be harsh, and the colours just don't look the way they should. Purpose-made projection screens use special fabrics that do the job right.
Projector screens come in standard sizes – which you should bear in mind as you decide on the screen size you're after – but you can always get a custom size screen made if need be. Either way, you'll need to know what size screen can be achieved in your size room.
Size versus image quality
As the image gets bigger, or you move closer to the screen, the quality of image deteriorates. If your screen gets too big (in relation to your viewing distance) the image will become chunky and grainy. Every imperfection will be glaringly obvious. If this happens, you need to reduce your image size or sit further away.
As a general rule, sit no closer than 2x the screen height e.g. if the screen is 5 feet high, sit 10 feet away.
What does 'throw ratio' mean?
'Throw ratio' refers to the relationship between how far away your projector is placed from the projector screen relative to the size of the image projected.
Different projectors have different lenses and each lens has a different throw ratio. A projector with a 'standard throw' lens might have a throw ratio of 2. That means for every 1 foot of screen size (measured diagonally) the projector will need to be two feet away.
What size can I expect?
To achieve a bigger picture, you need to move your projector further away from the wall i.e. increase the throw distance.
A general rule of thumb for projectors with a 'standard throw' lens is one foot of image (measured diagonally) for every two feet of space between the projector and screen e.g. for a five foot image a standard throw projector would need to be positioned ten feet away from the screen. This is a rough guide only and results vary by model.
For more flexible placement options, some projectors have a 'short throw' and/or 'long throw' feature built into them.
Short throw
Short throw (either a built-in feature or an extra lens) allows you to achieve a bigger image in a tighter space than with a standard throw lens. Some projectors, such as the Epson EMP-TW20 can produce a large 80" (180cm) image from just two metres away. This is useful, for example, if you have a small room and want a huge screen.
Long throw
Long throw (either a built-in feature or an extra lens) allows you to position the projector further away from the screen and produce a smaller, sharper image than with a standard throw. This is useful if you have a large, dedicated home theatre room and want to position your projector at the back of the room, out of sight. In this instance, a standard throw would produce an image that's too big.
Short, standard or long throw? What do you need?
When watching movies (etc) through a projector, screen-size is such a personal thing. The question of "How big is too big?" is up to the individual to decide.
If you've got a small room (less than 4 meters deep), you should probably consider projectors with a short throw capability. If you've got a medium or large room, look at where you'd like to position your projector and let that be your guide. If it's at the back of the room, you'll definitely be looking at either a standard or long-throw.
Ask an Expert
Before you buy a projector we recommend you discuss your plans with an entertainment specialist. Taking time to do this will ensure that you end up with the best possible result.