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This Ready Reckoner makes many assumptions in order to keep the information
collection simple. We have assumed:
- The screen has a 4:3 aspect ratio, as we are concerned with projecting computer images and not wide-screen television
- The distance from the screen to the front of the front row of seats is at least 1½ times the screen height
- The distance from the screen to the front of the back row of seats is no more than 4 times the screen height
- Each seat is 60cm wide and 30cm deep
- The rows of seats are 1m apart, measured from the back of one row to the back of the next
- There is a gap of 70cm between the back of the back row of seats and the back wall
- There are 70cm wide side aisles and, if any are indicated, central aisle(s) 1.4m wide
- There are no more than 10 seats in a block
- The internal screen of the projector is 3cm, measured diagonally
- A contrast ratio above 500:1 offers no discernable advantage unless the room is in pitch darkness apart from the projector
- We leave the choice of resolution up to you as this is dictated principally by the application you are running and by the capabilities of your computer graphics
- If a screen height is indicated which exceeds the height of the room, the room depth should be reduced and the Ready Reckoner re-started. In practice, there will therefore be some unusable space behind the back row of seats.
- If the indicated lens focal length is not available, the screen to projector distance should be changed and the Ready Reckoner re-started
- If the indicated brightness (Lumens) is unavailable, the ambient lighting should be changed and the Ready Reckoner re-started.
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