Well, I am working up some numbers for the school gym’s proposed projector installation. Projection can be quite a tricky business because you have to try to work out an optimum screen size for a venue and then with big installation projectors you are looking for the right lens as well for a long throw or short throw or whatever situation you have.
I started with the projection calculator here: http://www.elitescreens.com/index.php/component/content/article?id=264
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The projector model being Epson EB-G6350 but as this model is not listed the similar Powerlite Pro G6150NL was instead selected.
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Setting a custom aspect ratio of 16:10 (1.6:1) to begin with.
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Screen Gain 1.0
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Throw distance 20 metres
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Calculator lists 8 lenses but only 6 of these are current with the G6350 model. Of these only three have the range required to work at 20 metres.
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Long Throw Lens ELPLL06
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2.1 metres high, 3.9 metres diagonal, 3.3 metres wide.
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Throw range 17-23 metres.
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Seating distance range 4.3-19.9 metres.
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Image brightness 159 nits.
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Middle Throw Lens ELPLM04
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4.4 metres high, 8.4 metres diagonal, 7.1 metres wide.
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Throw range 17-25 metres.
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Seating distance range 9.2-45 metres.
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Image brightness 33 nits.
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Middle Throw Lens ELPLM05
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3 metres high, 5.6 metres diagonal, 4.7 metres wide.
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Throw range 17-25 metres.
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Seating distance range 6.2-28.5 metres.
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Image brightness 71 nits.
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Based on the above data the recommended choice of lens would be the ELPLL06. If we run the numbers again with a 4:3 screen which is the native aspect ratio for the G6350 (its resolution is 1024×768) then it comes up to a screen that is 2.5 metres high instead.