page 91
Digital Projection E-Vision Laser 4K Series
Reference Guide
CHOOSING A LENS
Rev A June 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
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
0.38 : 1 xed (UST) 0.82 m - 2.71 m
0.75 - 0.93 : 1 zoom 1.02 m - 12.7 m
0.76 : 1 xed 0.81 m - 5.08 m
1.25 - 1.79 : 1 zoom 1.33 m - 11.73 m
1.72 - 2.27 : 1 zoom 1.83 m - 14.9 m
2.22 - 3.67 : 1 zoom 2.36 m - 24.2 m
3.58 - 5.38 : 1 zoom 3.8 m - 35.35 m
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 =
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