Digital Projection Projector HIGHlite 740 Series User Manual

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Reference Guide
CHOOSING A LENS
Basic calculation example
1. Calculate the throw ratio using the formula.
Your screen is 4.5 m wide and you wish to place the projector 
approximately 11  m from the screen. The throw ratio will then be
  
11
4.5 = 2.44
2. Match the result with the lens table.
The lens matching a throw ratio of 2.44 is the 2.17 - 2.90 : 1 
zoom lens.
3. Check whether the lens covers the required throw distance. 
The range quoted for the 2.17 - 2.90 : 1 zoom lens is  2.7 - 15.4 
m. The required distance of 11 m is within the range.
Notes
  The basic calculation on this page 
does not take into consideration 
DMD™ and image size, which could 
affect the throw ratio. For a more 
complex and realistic calculation, 
see Full lens calculation  in this 
section.
  For information about individual lens 
part numbers, see Appendix A at 
the end of this document.
INFORMATION YOU NEED FOR THIS CALCULATION
• The throw ratio formula:
Throw distanceScreen width
Throw ratio =
• The lens table:
Throw ratios
Throw distance range
0.77 : 1 fixed lens 1.3 - 2.5 m (4.3 - 8.2 ft)
1.16 : 1 fixed lens 1.4 - 6.2 m (4.6 - 20.3 ft)
1.45 - 1.74 : 1 zoom lens 1.8 - 9.3 m (5.9 - 30.5 ft)
1.74 - 2.17 : 1 zoom lens 2.2 - 11.8 m (7.2 - 38.7 ft)
2.17 - 2.90 : 1 zoom lens 2.7 - 15.4 m (8.9 - 50.5 ft)
2.90 - 4.34 : 1 zoom lens 3.6 - 22.5 m (11.8 - 73.8 ft)
4.34 - 6.76 : 1 zoom lens 5.5 - 35 m (18 - 115 ft)
   
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CHOOSING A LENS
Full lens calculation
Introducing TRC
The choice of lens will affect the image size and will address discrepancies between the 
DMD™ resolution and the source.
When an image fills the height of the DMD™ but not the width, it uses less than 100% of 
the DMD™ surface. A lens chosen using the basic formula may produce an image that is 
considerably smaller than the actual screen.
To compensate for loss of screen space in such situations, you need to in\
crease the throw 
ratio using a Throw Ratio Correction (TRC).
Example
Fig. 1 illustrates a 4:3 image within a 1080p DMD™.
When a 1080p projector is used for a 4:3 image, the image does not fill the width of the 
DMD™, creating a pillarboxing effect - blank spaces to the left and right.
Fig. 2 shows the same image projected on a 4:3 screen using a standard lens (\
chosen with 
the basic calculation).
The DMD™ accurately fills the width of the screen; however, the pillarboxing is now part of the 
projected image and is transferred to the screen.
The DMD™ does not fill the height of the screen, which has caused letterboxing - further 
blank spaces at the top and bottom of the screen.
The image is now surrounded by blank space, which can be removed if the \
throw ratio is 
increased.
Fig. 3 shows the image projected on the same screen with a lens chosen using\
 TRC.
The increased throw ratio has allowed the 4:3 image to fill the 4:3 screen seamlessly.
Notes
 TRC can only be applied if greater 
than 1. If TRC is 1 or less, disregard 
it and calculate the throw ratio using 
the basic formula.
Fig. 1
Fig. 2
Fig. 3
   
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CHOOSING A LENS
Calculating TRC
To calculate TRC, use the following formula:
DMD™ aspect ratioSource aspect ratio
TRC =
TRC table
Alternatively, you can save time by referencing the following table, which shows the \
TRC value for some popular image formats:
1080pWUXGA
2.35:1 (Scope), 1920 x 817 pixelsTRC < 1, not usedTRC < 1, not used
1.85:1 (Flat), 1920 x 1037 pixelsTRC < 1, not usedTRC < 1, not used
1.78:1 (16:9), 1920 x 1080TRC = 1, not used (native resolution)TRC < 1, not used
1.66:1 (Vista), 1792 x 1080 pixelsTRC = 1.07TRC < 1, not used
1.6:1 (16:10), 1728 x 1080 pixelsTRC = 1.11TRC = 1, not used (native resolution)
1.33:1 (4:3), 1440 x 1080 pixelsTRC = 1.33TRC = 1.2
1.25:1 (5:4), 1350 x 1080 pixelsTRC = 1.42TRC = 1.28
Notes
 
TRC can only be applied if greater 
than 1. If TRC is 1 or less, disregard 
it and calculate the throw ratio using 
the basic formula.
   
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CHOOSING A LENS
Calculating the throw ratio with TRC
1. For TRC > 1, amend the basic throw ratio formula as follows:
Throw distance
Screen width  x TRC
Throw ratio =
2. Once a throw ratio is established, identify the matching lens from the t\
able:
Throw ratiosThrow distance range
0.77 : 1 fixed lens1.3 - 2.5 m (4.3 - 8.2 ft)
1.16 : 1 fixed lens1.4 - 6.2 m (4.6 - 20.3 ft)
1.45 - 1.74 : 1 zoom lens1.8 - 9.3 m (5.9 - 30.5 ft)
1.74 - 2.17 : 1 zoom lens2.2 - 11.8 m (7.2 - 38.7 ft)
2.17 - 2.90 : 1 zoom lens2.7 - 15.4 m (8.9 - 50.5 ft)
2.90 - 4.34 : 1 zoom lens3.6 - 22.5 m (11.8 - 73.8 ft)
4.34 - 6.76 : 1 zoom lens5.5 - 35 m (18 - 115 ft)
3. Ensure the required throw distance is within the range of the matching l\
ens.
Notes
 
TRC can only be applied if greater 
than 1. If TRC is 1 or less, disregard 
it and calculate the throw ratio using 
the basic formula.
   
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CHOOSING A LENS
Full lens calculation example
Your screen is 4.5 m wide; you wish to place the projector 
approximately 11  m from the screen. You use a WUXGA 
projector; 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 1.74 - 2.17 : 1 
zoom lens.
4. Check whether the lens covers the required throw distance.
The range quoted for the 1.74 - 2.17 : 1 zoom lens is  2.2 - 
11.8 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)
WUXGA
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
0.77 : 1 fixed lens 1.3 - 2.5 m (4.3 - 8.2 ft)
1.16 : 1 fixed lens 1.4 - 6.2 m (4.6 - 20.3 ft)
1.45 - 1.74 : 1 zoom lens 1.8 - 9.3 m (5.9 - 30.5 ft)
1.74 - 2.17 : 1 zoom lens 2.2 - 11.8 m (7.2 - 38.7 ft)
2.17 - 2.90 : 1 zoom lens 2.7 - 15.4 m (8.9 - 50.5 ft)
2.90 - 4.34 : 1 zoom lens 3.6 - 22.5 m (11.8 - 73.8 ft)
4.34 - 6.76 : 1 zoom lens 5.5 - 35 m (18 - 115 ft)
DMD™ aspect ratio
Source aspect ratioTRC =
Throw distance
Screen width x TRCThrow ratio =
   
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SCREEN REQUIREMENTS
Screen Requirements
Fitting the image to the DMD™
If the source image supplied to the projector is smaller than the DMD™ resolution, the image will not fill the DMD™. The following examples 
show how a number of common formats may be displayed, depending on your \
DMD™ resolution.
1080p images displayed full width
Notes
2.35:1(Scope) 
 =  817 pixels
full width = 1920 pixels
1.85:1 
 = 1037 pixels
16:9 = 1.78:1  
= 1080 pixels 
(native resolution)
   
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SCREEN REQUIREMENTS
1080p images displayed full heightNotes
4:3 = 1.33:1 = 1440 pixels
full height = 1080 pixels
1.66:1 (Vista) = 1792 pixels16:9 = 1.78:1 = 1920 pixels  
(native resolution)
16:10 = 1.6:1 = 1728 pixels
   
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SCREEN REQUIREMENTS
WUXGA images displayed full width
WUXGA images displayed with a height of  1080 pixels
full width = 1920 pixels
2.35:1(Scope)  =  817 pixels
1.85:1 
 = 1037 pixels
16:9 = 1.78:1  
= 1080 pixelsfull height  
= 1200 pixels
Notes
4:3 = 1.33:1 = 1440 pixels
full height  
= 1200 pixels
1.66:1 (Vista) = 1792 pixels 16:10 = 1.6:1 = 1728 pixels
max possible  image height 
 
= 1080 pixels
full width = 1920 pixels
   
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SCREEN REQUIREMENTS
WUXGA images displayed full heightNotes
 Only WUXGA or UXGA images 
can fill the full height of the DMD ™, 
using all 1200 pixels without scaling.
 full height = 1200 pixels
WUXGA = 16:10 = 1.6:1 = 1920 pixels UXGA = 4:3 = 1.33:1 = 1600 pixels
   
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SCREEN REQUIREMENTS
Diagonal screen sizes
Screen sizes are sometimes specified by their diagonal size (D). When dealing 
with large screens and projection distances at different aspect ratios, it is more 
convenient to measure screen width (W) and height (H).
The example calculations below show how to convert diagonal sizes into w\
idth and 
height, at various aspect ratios.   
2.35:1 (Scope) 
W = D x 0.92 H = D x 0.39
1.85:1 
W = D x 0.88 H = D x 0.47
16:9 = 1.78:1 (native aspect ratio for 1080p projectors) 
W = D x 0.87 H = D x 0.49
1.66:1 (Vista) 
W = D x 0.86 H = D x 0.52
16:10 = 1.6:1 (native aspect ratio for WUXGA projectors) 
W = D x 0.85 H = D x 0.53
Notes
D = diagonal
W = width
H = height 
   
Digital Projection HIGHlite 740 Series 
Rev I Februar y 2015