page 86
Digital Projection M-Vision Laser 18K Series
Reference Guide
CHOOSING A LENS
Rev D October 2019
Full lens calculation example
Your screen is
4.5 m
wide; you wish to place the projector
approximately
10 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:
10
4.5 x 1.2
Throw ratio =
=
1.85
3. Find a match in the lens table.
The table shows that the matching lens is
the 1.50 - 2.00 : 1
zoom lens
.
4. Check whether the lens covers the required throw distance.
The focus range quoted for the 1.50 - 2.00 : 1 zoom lens is
2 - 12 m
. The required distance of 10 m is within the range.
Notes
The lens table shown on this page
includes High Brightness lenses
only. For a full list, see
Appendix A
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 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
1.20 - 1.56 : 1 zoom
1 m - 8 m
1.50 - 2.00 : 1 zoom
2 m - 12 m
2.00 - 4.00 : 1 zoom
2.5 m - 15 m
4.00 - 7.00 : 1 zoom
4 m - 42 m
DMD™ aspect ratio
Source aspect ratio
TRC =
Throw distance
Screen width x TRC
Throw ratio =
