Ultra short throw projector
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).
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.)
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.