page 75
Digital Projection E-Vision Laser WQ120 Series
CHOOSING A LENS
Rev A May 2018
Full lens calculation example
Your screen is
4.5 m
wide; you wish to place the projector
approximately
11 m
from the screen. The source is
4:3
.
1. Calculate TRC as follows:
1.60
1.33
TRC =
= 1.20
2. Calculate the throw ratio:
11
4.5 x 1.20
Throw ratio =
=
2.04
3. Find a match in the lens table.
The table shows that the matching lens is
the 1.71 - 2.25 : 1
zoom lens
.
4. Check whether the lens covers the required throw distance.
The focus range quoted for the 1.71 - 2.25 : 1 zoom lens is
1.02m - 12.7m
. The required distance of 11 m is within the
range.
Notes
The lens table shown on this page
includes High Brightness lenses
only. For a full list, see
at the end of this document.
INFORMATION YOU NEED FOR THESE CALCULATIONS
•
The TRC formula
•
The TRC table (to use instead of the formula)
2.35:1 (Scope)
TRC not used
1.85:1 (Flat)
TRC not used
1.78:1 (16:9)
TRC not used
1.66:1 (Vista)
TRC not used
1.6:1 (16:10)
TRC = 1.0 not used (native aspect ratio)
1.33:1 (4:3)
TRC = 1.20
1.25:1 (5:4)
TRC = 1.28
•
The throw ratio formula
•
The lens table:
Throw ratios
Focus range
0.79 - 0.99 : 1 zoom
1.02 m - 12.7 m
1.32 - 1.89 : 1 zoom
1.33 m - 11.73 m
1.82 - 2.40 : 1 zoom
1.83 m - 14.9 m
2.34 - 3.90 : 1 zoom
2.36 m - 24.2 m
DMD™ aspect ratio
Source aspect ratio
TRC =
Throw distance
Screen width x TRC
Throw ratio =
