page 80
Digital Projection M-Vision 930 Series
Reference Guide
CHOOSING A LENS
Rev C February 2015
Full lens calculation example
Your screen is
3.5 m
wide; you wish to place the projector
approximately
6.8 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:
6.8
3.5 x 1.2
Throw ratio =
= 1.62
3. Find a match in the lens table.
The table shows that the matching lens is
the 1.56 - 1.86 : 1
zoom lens
.
4.
Check whether the lens covers the required throw distance.
The range quoted for the 1.56 - 1.86 : 1 zoom lens is
2 - 12.4 m
. The required distance of 6.8 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
Throw distance range
0.84 - 1.03 : 1 zoom lens
1.5 - 10 m (4.9 - 32.8 ft)
1.56 - 1.86 : 1 zoom lens
2 - 12.4 m (6.6 - 40.7 ft)
1.85 - 2.40 : 1 zoom lens
2.5 - 15.9 m (8.2 - 52.2 ft)
2.40 - 4.00 : 1 zoom lens
4 - 26.6 m (13.1 - 87.3 ft)
DMD™ aspect ratio
Source aspect ratio
TRC =
Throw distance
Screen width x TRC
Throw ratio =
