Sony VPL-VW50 Operating Instructions Manual page 51

Blanking
This feature allows you to adjust the displayable region within
the four directions of the screen.
Select each screen edge "left / right / up / bottom" on the Blanking
adjustment screen with M / m buttons. Adjust the desired Blanking
value with < / , button.
Note
When both the Blanking and the V Keystone are adjusted at the
same time, the Blanking cannot be adjusted correctly. When using
the Blanking, make sure that you set the V Keystone to "0".
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