Ultra short throw projector

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1 Introduction

A projector with ultra short throw capabilities allows positioning it and a connected laptop very closely to the screen (between a 10 and 70 cm) rather than somewhere in the back or in the middle of the audience. This technology is also used with interactive whiteboards.

Throw ratio is defined as defined as distance from screen divided by the diagonal.

  • Ultrashort throw can be as low as 0.19 : 1. A more typical value is 0.25:1
  • Short throw is about 0.4 : 1
  • Normal projectors are about 1.2 : 1

Let's look at an example:

  • You need to project on a large whiteboard, e.g. a width of 200cm (79in), i.e. for a meeting in your office, and you got a mid-range projector with a 0.25 : 1 ratio.
  • The diagonal of a 16:9 projector (what most modern computer screen have) is 229cm (about 90.3''). Its height would be 112.5cm
  • 229 * 0.25 means that the projector should sit 57cm away. That would work from a desk sitting against a wall (80cm width).

Other distances with a ratio of 0.25

  • 260cm (300cm diagonal, i.e. 120'' and 147 height): min. distance is 75cm. This the maximum for most models.
  • 300cm (344 diagonal and 168 height): min. distance is 86cm. That is probably the maximum for high ends (nov. 2017)
  • 500cm (574 diagonal and 280 height): distance is 140cm. Not sure that this could work with any projector !!

Use in poster exhibition spaces:

  • A1 landscape width, 84.1cm: distance is 24cm.
  • A0 landscape width, 118.9cm: distance is 34cm.

However, a minimal distance of 30cm (12) is needed for some projectors. Very expensive ones can be closer. Less expensive models may require 45cm (18).

2 Use

Short throw projectors have the following advantages:

  • fairly easy transportation. However, some models can be quite heavy.
  • Have wireless interfaces
  • People can not trip over wires
  • The presenter will not experience the project light in her/his eyes
  • Can achieve a brighter images with less lumen (e.g. short throw projectors with 3000 or 3500 lumens achieve the same as 5000 lumen standard ones).

Major use cases:

  • Small conference rooms and offices
  • Exhibits (e.g. poster sessions at conferences, trade shows)
  • Home theatre use in small rooms
  • Replacement for video walls (in some situations).

Disadvantages:

  • Need a bit more work to set up. Most projectors cannot auto-focus.
  • Does not project well on rough surfaces, since tiny bumps can create shadows when the beam hits sideways (!!). I.e. ideally one should use a projector screen or at least a flat whiteboard or similar.

Spiced up models:

  • Have pens or hand movement detection
  • Can connect with all sorts of input and output (mobile apps via bluetooth, smart RV controls, audio bluetooth output, etc.)

3 Models

As of Nov 2017, models cost between 1000 and 3000 CHF/Euros/$. Even fairly expensive models sometimes only support full HD which is nowadays a bad resolution for people working with code and data.

Model Resolution ratio lumen contrast ratio (?) Technology Weight Wireless

Connectivity

Distances Diagonals Price (approx.)
BenQ W1600UST Full HD 0.23 3300 13'000:1 DLP 6.2kg Android and Ios input, bluetooth out 1425 CHF
BenQ MH856UST Full HD 0.35 3500 10'000:1 DLP 5kg
BenQ MX842UST WUXGA 0.47 3000 13'000:1 DLP 5.5kg 152 to 254cm (60'' to 120'') 2200 CHF
LG PF1000UT Adagio Full HD 0.29 1000 150'000:1 DLP 1.5kg 1400 CHF
LG HF85JS Allegro Full HD 0.19 1500 150'000:1 DLP 3kg Android and IOS 12cm for 254cm 20 cm for 304cm 228 cm – 304,8 cm (90“-120“) 2300 CHF
LG PF1000U Full HD 0.29 1000 150'000:1 DLP 1.5kg simple 1090 CHF
Philips Screeneo 2510 Full HD 0.21 2000 200'000:1 DLP 8.3kg 1900CHF
DELL S518WL WXGA 0.52 3200 20'000:1 DLP 1600CHF
DELL S560P Full HD 3400 10'000:1 DLP 4.7kg interactive pens or hand movements for the T version
DELL S7180QL 4K 0.19 5000 100'000:1 DLP 15kg Bluetoth, 6500CHF
Optoma GT5500+ Full HD 0.25:1 3600 25,000:1 DLP 5kg ? 1666 CHF
Optoma EH320UST Full HD 0.25:1 4000 20000:1 DLP 2030 CHF
Optoma EH320USTi

(interactive!)

Full HD 0.25:1 4000 20,000:1 DLP 5kg ? 2100 CHF

I got very strange figures for contrast ratio. Maybe the numbers I found with a reseller mean different things . The LG PF1000UT Adagio is maybe a good solution for a light-weight not too expensive model, but it is little lumen (room needs to be dark). The BenQ W1600UST has much better specifications, but is heavier.

Screen resolutions:

WXGA = 1280 x 800
WUXGA = 1600 x 1200
Full HD = 1920x 1080 px
4K = 3840 x 2160px

Not sure that the figures are correct ! Please check yourself.