page 87
Digital Projection E-Vision Laser 7500, 8500 & 10K Series
Reference Guide
CHOOSING A LENS
Rev D August 2017
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:
1.6
1.33
TRC =
= 1.2
2. Calculate the throw ratio:
11
4.5 x 1.2
Throw ratio =
=
2.04
3. Find a match in the lens table.
The table shows that the matching lens is
the 1.72 - 2.27 : 1
zoom lens
.
4. Check whether the lens covers the required throw distance.
The focus range quoted for the 1.72 - 2.27 : 1 zoom lens is
1.83 - 14.9 m
. The required distance of 11 m is within the
range.
Notes
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 not used (native resolution)
1.33:1 (4:3)
TRC = 1.2
1.25:1 (5:4)
TRC = 1.28
•
The throw ratio formula
•
The lens table:
Throw ratios
Focus range
0.82 m - 2.71 m
1.02 m - 12.7 m
0.81 m - 5.08 m
1.33 m - 11.73 m
1.83 m - 14.9 m
2.36 m - 24.2 m
3.8 m - 35.35 m
0.38 : 1 fixed (UST)
0.75 - 0.93 : 1 zoom
0.76 : 1 fixed
1.25 - 1.79 : 1 zoom
1.7
3
- 2.27 : 1 zoom
2.22 - 3.67 : 1 zoom
3.58 - 5.38 : 1 zoom
5.31 - 8.26 : 1 zoom
5.59 m - 54.8 m
DMD™ aspect ratio
Source aspect ratio
TRC =
Throw distance
Screen width x TRC
Throw ratio =
