BenQ SP870 user manual Select your screen size

How to determine the position of the projector for a given screen size

1.Select your screen size.

2.Refer to the table and find the closest match to your screen size in the left columns labelled "4:3 screen diagonal". Using this value, look across this row to the right to find the corresponding average distance from screen value in the column labelled "Average". This is the projection distance.

3.On that same row, look across to the right column and make note of the "Vertical offset in mm" value. This will determine the final vertical offset placement of the projector in relation to the edge of the screen.

4.The recommended position for the projector is aligned perpendicular to the horizontal center of the screen, at the distance from the screen determined in step 2 above, and offset by the value determined in step 3

above.

For example, if you are using a 120-inch screen, the average projection distance is 4416 mm and with a vertical offset of 210 mm.

If you place the projector in a different position (to that recommended), you will have to tilt it down or up to center the image on the screen. In these situations, some image distortion will occur. Use the Keystone function to correct the distortion. See "Correcting keystone" on page 28 for details.

How to determine the recommended screen size for a given distance

This method can be used for situations where you have purchased this projector and would like to know what screen size will fit in your room.

The maximum screen size is limited by the physical space available in your room.

1.Measure the distance between the projector and where you want to position the screen. This is the projection distance.

2.Refer to the table and find the closest match to your measurement in the average distance from screen column labelled "Average". Check that your measured distance is between the min and max distances listed on either side of the average distance value.

3.Using this value, look across that row to the left to find the corresponding screen diagonal listed in that row. That is the projected image size of the projector at that projection distance.

4.On that same row, look across to the right column and make note of the "Vertical offset in mm" value. This

will determine the final placement of the screen in relation to the horizontal plane of the projector. For example, if your measured projection distance was 4.5 m (4500 mm), the closest match in the "Average" column is 4416 mm. Looking across this row shows that a 120-inch screen is required. If you can only obtain metric sized screens, the listed screen sizes on either side of the 120-inch screen are the 3.0 m (3000 mm) and 3.5 m (3500 mm) screens.

Checking the min and max projection distance values for these screen sizes, indicates that the 4.5 m measured projection distance will also fit the 3.0 m (3000 mm) size screen. Be aware that these different screens have different vertical offset values.

There is 3% tolerance among these numbers due to optical component variations. BenQ recommends that if you intend to permanently install the projector, you should physically test the projection size and distance using the actual projector in situ before you permanently install it, so as to make allowance for this projector's optical characteristics. This will help you determine the exact mounting position so that it best suits your installation location.

14 Positioning your projector