Projector FAQ
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Buyers Guide
- Home Theatre
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Projectors
- Acer
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- Hitachi
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- Panasonic
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Screens
- Which Screen?
- Portable Screens
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- Motorised Screens
- Outdoor Screen
- Whiteboard Screens

Accessories
- Cables / Adapters
- Lamps
- 3D Glasses
- Document Cameras
- Bluray Player
- Presentation Remotes
- Projector Mounts

 

Please select the topic you like more information on:
DLP vs. LCD Contrast Brightness
Noise Throw Distance & Projection Size Inputs
Aspect Ratio Resolution Keystone
Lamp Life Other 3D Projectors
Short Throw / Ultra Short Throw Projectors LED Projectors Pico/Mini/Ultra Portable Projectors

DLP VS LCD Technology


In an LCD (liquid-crystal display) projector light from a single lamp is directed to a trio of miniature LCD panels that process the red, green, and blue light components separately. The pixels in each panel contain a liquid-crystal material that regulates the amount of light passing through them by twisting and untwisting in response to electrical voltages. After exiting the LCD panels, the three colored beams are combined by a prism and projected onto the screen by a lens.


Most DLP (Digital Light Processing) projectors have a single chip and a spinning colour wheel that chops white light from a lamp into a sequence of red, green, and blue beams (sometimes yellow and white too). The beams are reflected from the chip which contains hundreds of thousands of tiny mirrors. These mirrors pivot thousands of times a second to control the brightness of the pixels and are synchronized to display a red, green, or blue projection that the eye blends into a full-color image.

The Difference:
Ask us just 5-8years ago and we would have said there was a big difference in image quality and reliability between the 2 popular technologies, today though with so many changes occurring over the past decade there is very little difference. We generally recommend not to worry too much about the technology being used, the overall quality and suitability of a projector really comes down to the individual model. There are some great DLP's on the market and some great LCD's too.

In the past LCD was known for more accurate colours, a slightly sharper image, and for being more light-efficient, which means they produce brighter images using less power. LCD projectors were also known for some negatives such as a screen door effect and lower contast/black levels. The screen door effect was basically the gap between the pixels making the image look like you were looking through a screen door.
All of these 'disadvantages' of LCD have been addressed by the brands so there are not too many negatives anymore. Over the past decade HD and FULL HD resolutions have pretty much removed the screen door issue and filters or an inbuilt Iris function has improved contast substantially.

On the DLP side some postives were the improved smoothness of the image, no screen door effect (due to the pixels being closer), and improved contrast. Some negatives were that a small percentage of the population could see a "rainbow effect". This effect basically looks like a rainbow of colours across the screen and is typically visible when you move your eyes across the screen rapidly. This effect is only visible with a very small percentage of the population in varying severity. The rainbow effect is caused by the refreshing of the colours on screen as the colour wheel spins. As with the issues LCD projectors faced in the past the DLP companies have been working to improve the technology. DLP projectors now use faster colour wheels and use more segments... this improves colour reproduction and reduces the amount of people who can see the rainbow effect substantially.
As LCD and DLP technology are so similar nowadays when selecting a projector it is best to compare the specifications and features and not to worry as much about the technology being used inside the unit, it doesn't matter as much as in the past since both technologies can produce brilliant pictures.

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Contrast Ratio

A term defining how far the whitest whites are from the blackest blacks. If the peak white value is significantly different than the peak black value the signal is said to have high contrast resulting in well defined sharp colour's and shading. The Higher the better. A contrast of 400:1 means that the blackest black on the image will be 400 times darker than the whitest white.

The contrast ratio is an important specification to look at should you be looking for a home theatre projector or when you wish to project in a darkened room. It is not of much importance for data/business projectors though as the contrast is usually washed out by the ambient light in the room.

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Brightness
The brightness of the projector (ie how bright the image will be) is rated by ANSI LUMENS.
The recommended brightness level varies depending on use and room conditions.

  • Home theatre projectors will range from about 2000 lumens up to about 2500 lumens brightness. When you're watching a movie you will most likely dim most of the light from the room, so a bright projector is not only unnecessary it will be overpowering in a dim room. Home theatre projectors generally focus on providing high detail, accurate colours, and high contrast to give the best picture possible.
  • Presentations in a dim room allows you to decide from projectors around the 2000- 3000 lumen brightness level. Presentations require people to be able to read from charts sheets and other small texts and therefore you will need a little more brightness than home theatre.
  • Presentations in a lit room will require from 3000 to 5000 Lumens brightness. This will ensure that the image is visible on the wall/screen in most lit rooms. Just remember the larger the screen and the brighter the room the brighter the projector will have to be. 3000 lumens is usually enough for a boardroom sized area, while 4000+ lumens is better for small halls or areas with lots of natural light.
  • Larger venues presentations with a lit room/hall. In this situation I would recommend 4000 lumens and above. The larger the screen has to be and the more light that comes in the brighter the projector will have to be. For a 2m wide picture in a well lit room 4000 lumens is normally fine, for a 4m wide picture in a well lit room you would be best to jump up to around 6000 lumens or higher.

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Noise
The noise rating of each projector is also a consideration. Basically every projector has a very hot lightsource providing the light for the picture. The projector is equipped with fans that are designed to cool the lightsource and prolong it's life. The fans will be quieter on Economic mode as you are basically turning down the lamps output and therefore the heat produced. Generally anything below 30 dB is fairly quiet. Home theatre projectors in particular should be quiet as you don't want to be sitting in suspense at a quiet point in the movie and hear an overwhelming buzzing noise from the fans..

When buying a portable projector the noise level is generally higher; the fans will have to be smaller and spin at a faster rate to provide the same amount of cooling.

Projector noise ranges from 22dB for the large home theatre models, up to 40dB for the ultra portable units.

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Throw Distance and Projection Size
One thing that can trip up customers is Throw Distance & Projection Size. Different projector models use different lenses, all with different zooms and throw distances. Each projector must be positioned within a certain distance for a certain image size. This distance can vary by quite alot between each model. Some projectors need to be very close (short throw) and some fairly far away (long throw). Just Projectors has a Throw Distance Chart available on the 'More Information' page for most projectors to allow customers to get an idea of installation size. If you are replacing an existing projector and want the new unit to sit at the same position you may get a different image size... if you must get the same image size feel free to contact Just Projectors staff so we can make sure whatever replacment you get will get you the correct picture size.

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Inputs
Many people do not really consider the importance of having the right inputs. You should pick a projector with the right connections for your equipment.

The hierarchy of video quality:

  Best Quality Digital High Definition video DVI or HDMI
  Good Quality Analogue High Definition Video Component, VGA (15pin D-sub), BNC
  Low Quality Analogue Low Definition Video S-Video or Composite video

HDMI - High-Definition Multimedia Interface
This connection has basically taken over and is now featured on almost all projectors. It is the highest quality type of connection and is widely used on home theatre equipment as well as on computers. Be sure to use a v1.4 HDMI cable if you wish to play 3D, the older v1.3 HDMI cables cannot transmit 3D signals.

DVI
Digital Visual Interface. The DVI port is similar to the HDMI, as it also uses digital signals to transmit video to the projectors. It has become less common in recent years with many projector brands changing to HDMI. Picture quality between DVI and HDMI is the same.

D-SUB 15 pin (VGA)
Also called a D-connector, RGB, or VGA. A type of connector commonly found on computers, monitors, and projectors... D-type connectors have a "D-shaped" angled housing and have 15 pins.
VGA is still the most commonly found connector on a projector but is slowly being replaced with HDMI. VGA transmits in analogue so whilst picture quality is still quite good if you are using a FULL HD projector we recommend using HDMI instead.

RCA (Component)
The higher quality analogue method of transmitting video signals, which operates by splitting up the red the green and the blue colours in the signal and then synchronizing them on the other end, making a clearer signal. Many projectors accept component through an adapter cable connecting directly into the 15pin D-sub (sometimes called the VGA port).

BNC (R/G/B/H/V)
(Bayonet-Neill-Concelman) - A not so common connector used to terminate coaxial cables. BNC is also referred to as Bayonet Network Connector. This is only used on a few large venue projectors.


S-Video
Small multi pin connector that carries separate brightness and color signals from a source component like a DVD player or satellite receiver to a TV set. This is an old fashioned lower quality connection but is still featured on most projectors.

RCA (Composite)
A common, standard connection method used to transmit analog audio and video signals between devices. Commonly used on most receivers, televisions, satellite receivers, VCR's, game console systems and speakers. This is an older fashioned lower quality connection.

USB
This connection on projectors is used for two purposes:
1. Most commonly it is used as a feedback connection to the computer or laptop, allowing you to click next slide etc on the wireless projector remote and control the presentation.

2. In some cases it is used with PC FREE presentation projectors allowing you to plug a USB memory stick into the projector and it can project with no PC straight through the projector. Some basic projectors will read picture files like Jpegs via this function and some will be able to do a proper presentations (after some formatiing to the powerpoint presentation.

3.5mm Jack
Much like the headphone connection on your walkman or ipod, the stereo mini jack is used to transmit audio into the projector. In some projectors this connection is also used for the 12v Trigger function. This function can allow a motorised screen to lower automatically when the projector is turned on.

D-sub 9pin (RS-232)
Most commonly it is used for control when wiring a projector into a control panel on the wall. In Some cases it is used for diagnosis when servicing.

RJ-45 (LAN Connection)
Some projectors allow you to connect to it through a normal network connection giving access to anyone on the network. This connection is predominantly used for control; turning on off and monitoring lamp life etc. Some projectors allow for the image to be sent via LAN.

Wireless WIFI (802.11b/802.11g/802.11n)
Some projectors come equipped with wireless connections. Allowing you to connect any PC and in some cases several PC's to the projector. This connection will in most cases require some software to be installed onto to computer

A wireless connection is not as good as a standard cable connection with a slower frame rate. For video a cable connection is recommended.

In some cases an upgrade module will have to be connected or WiFi card through USB.


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Resolution
A Native Resolution is essentially a measurement for the number of pixels being projected. The most common measurements for projectors are:
SVGA - 800x600
XGA - 1024x768
WXGA - 1280x800 (HD)
WUXGA - 1920x1080 (Full HD)
or 1920x1200

Both WXGA and WUXGA resolutions are widescreen, these are what we recommend for use with all modern computers (which are now widescreen too).
Both WXGA and WUXGA are fine for fairly detailed presentations, obviously the higher the resolution the better though... so if you are projecting really high detail quite often it may be best to upgrade to a WUXGA model

For home theatre use there is really only 1 resolution to get, and that is WUXGA 1920x1080.This is FULL HD. All home theatre grade projectors now use this resolution to give the best detail.

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Aspect Ratio (standard/widescreen)
The standard proportion in width to height for a projector used to be 4:3, but modern projectors have a widescreen format of 16:9 or 16:10. Almost all new computers are designed in the widescreen 16:10 or 16:9 formats so if the budget allows we normally recommend getting a 16:9 or 16:10 projector (which means a WXGA or WUXGA resolution).

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Keystone Correction
When you position a projector well above the picture and point it down, or below the picture and point it up your image will appear a bit skewed. The same will happen if you have the projector off to the left or right of the image.. the picture will end up having some distortion as per the below images.
Almost every projector now features Vertical Keystone Correction. This is a feature in the menu that allows you to manually adjust the image to 'square it up' or remove the distortion. Some projectors even have Automatic Vertical keystone correction that detects the angle in projection so does the correction automatically.
Horizontal keystone correction is not very common. It works the same as vertical keystone correction however fixes the distortion caused by having the projector too far left or right of the image.
Lens Shift is featured on some larger projectors which allows you to move the image up/down/left/right without the need to tilt or angle the projector. Because the projector is not being angled no keystone correction is required. As lens shift adds a fair bit to the size of the lens it is usually only featured on some larger home theatre projectors.

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Lamp Life
A major concern of many projector buyers is the lamp life. Projector lamps can be expensive and while they differ from model to model they generally range from $100-$400. Projector brands give a rating of lamp life with each projector so you know roughly how long the lamp usually will last for. If a lamp life is advertised as 'up to 5000 hours', this means on the most economic setting you should hopefully get near 5000hours of use. If you have the projector on a 'bright' mode you will get less hours.

Some models offer a long lamp life of up to 10,000 hours making them a very good buy in the long run.

While 3000 hours may not sound like much but even under fairly heavy use it does tend to last quite a while:
e.g. A 3000hour lamp used for 2 hours a day every day most liekly will last you about 4 years.

There are now a new breed of projectors with LED and LED/LASER based lighting systems. These can offer the same image quality but with a much longer lightsource life. Some offer a lamp life of 20,000 hours and, although the light source is not replacable, with a lamp life like that used for 2 hours a day every day it would last you up to 27 years. (Some LED based projectors will offer a much lower brightness so it is best to check the lumen rating in the specifications)

Extending Lamp Life
When installing plug in bulbs, be sure the lamps are seated completely. The tendency is to stop at the first sign of resistance. Continue to apply force at the base of the lamp until you are sure the lamp is secure.

Switching Projector Off
Always switch off using the remote control and not by disconnecting the power, the projector will invariably go into a cool down mode where the image is turned off and the fan accelerates to cool the lamp in a controlled manner. The temperature of an operating lamp is many 1,000's of degrees. Disconnecting the power to the projector prior to the above process causes the glass in the lamp to cool unevenly and could result in a stress fracture and early lamp failure.

Shock and Vibration
Lamp failure can be due to mechanical shock. A hot lamp is very fragile, you should always make sure that the unit is turned off and the lamp is cool before moving the unit. Once cool they are fine to be carried around just like a laptop.

Economy mode
If your projector is equipped with a "high/low lamp" switch you can extend your average lamp life by using the "low lamp" or "ECO" position whenever possible.

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3D Projectors
Many projectors now come with 3D compatibility. Projectors use Active 3D systems, this means the glasses must be compatible active shutter 3D glasses (unfortuantely your $2 passive glasses from the local cinema will not work).
Different brands use slightly different 3D systems, BenQ & Optoma for example use DLPLINK, Epson use its own RF system, while Panasonic use IR.

For more information visit our 3D projectors page.


Short Throw / Ultra Short Throw Projectors
The new buzz word in installation projectors is the short and ultra short throw range. These offer a much closer installation distance while still giving you a large image size.

The Benefits
Having a projector closer to the screen or wall avoids shadows of the presenter and stops the presenter from being blinded by the projectors light.

The Drawbacks
The optics involved in making the image larger make the projector heavier and larger. They have limits on the image size they can produce (normally up to 110"). The short throw projectors can also be more expensive.

Short Throw
short Throw
Short Throw
There are also two categories within short throw projectors; "Short Throw" and "Ultra Short Throw" Projectors.
A "short throw" projector has a magnification lens and requires an installation distance of roughly 1-2metres for a decent image size.
"Ultra short throw" projectors use magnification mirrors and allow for a closer distance normally within half a metre. These are usually more expensive and can be wall mounted just above the wall/screen further cutting down the throw distance.
Ultra Short Throw
Ultra Short Throw

 

LED Projectors
Most projectors' light source is a high pressure mercury lamp providing high brightness and a lamp life of up to 10000 hours. These then get replaced and cost around the $300 mark (depending on the model). Some of the newest range of projectors have replaced this with an LED light source which gives you a longer lamp life of 20,000 hours (never needing replacing).

"LED Projectors" generally have a brightness level between 50 and 1000 lumens, so much less than a lamp powered projector. This is fine for a small picture enough for half a dozen people or in a darkened room maybe around 10-15.

"LED Laser Projectors" are the newest addition to the projector lineup where the LED is boosted with a laser giving you the long lamp life with a high brightness between 2500 lumens and 4000 lumens allowing for use in conference rooms and classrooms. Casio have now made its entire range LED/LASER based.


Mini Pico & Ultra Portable Projectors
With the new option of using LED's to power a projector there is a new range of projectors that have become smaller and easier to carry. The smaller it is the less the power though so the pocket sized projectors aren't recommended to use with large groups.

Pico Projector

"Pico Projectors" are the smallest and most portable units around 250grams in weight and can sometimes even fit into a pocket. They are perfect for presentations with small groups up to 6 people. They will normally have around 100 lumens brightness limiting the presentation to a small image size.

Pico Projector

"Mini Projectors" are a portable unit that can fit into a small case weight around 1kg and are perfect for presentations with small groups up to 12 people. They will normally have around 500-1000 lumens brightness limiting the presentation to a medium image size.

Pico Projector

"Ultra Portable Projectors" are a portable unit that can fit into a small case weight around 2kg and are perfect for presentations with larger groups up to around 50 people. They will normally have around 3000 lumens brightness allowing for presentations in lit rooms with a large image size.

Short Throw

 

LED PROJECTOR
LED Projector

LED LASER PROJECTORLED Laser Projector

 

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Other Questions
Please contact us if you'd like more information general@gmmultimedia.com.au or 1300 739 131.


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