Cinema Projectors: What You Need to Know
There is a quite bewildering array of differences between home cinema projectors and the following information should help you to choose the best one for you. Please note that this information refers to home cinema rather than data projectors. The significant differences
between projectors are listed and explained below:
Resolution refers to the numbers of dots or ‘pixels’ that make up the picture you see. Generally speaking, more pixels will give you a clearer image. Almost all home cinema projectors available today have a resolution of 1920 x 1080 pixels which is also known as Full HD. The “next big thing” in TVs and projectors is 4K Ultra HD which has a resolution of 3840 x 2160 pixels, four times as many as Full HD.
The brightness of your projector is measured in lumens (or ANSI lumens). The bigger the number, the brighter the image! However, brighter images tend to have more washed-out (i.e. greyer) blacks. So, if you are planning to watch your projector in a darkened room, you can use a projector with a brightness of around 1000-1200 lumens. If you are going to be watching your projector in a room that will have a lot of ambient light (i.e. during the day with no curtains or blinds) you will need a brightness of 1600-2000 lumens or more.
This describes the difference between the black levels and the white levels of the projected image. A contrast ratio of 10,000:1 means that the white level is 10,000 times brighter than the black level. Different manufacturers calculate their contrast ratios in different ways so it is not always possible to compare projectors with each other.
This is the ratio of the width of the projected image to its height. Most projectors have an aspect ratio of 16:9 (1920 x 1080 Full HD, for example) which is also known as widescreen. Other common aspect ratios are
4:3 ( the format in which old TV shows were recorded) and 2.35:1 (also known as anamorphic) which is the format in which many films are presented in the cinema. An image shown on a screen of the wrong aspect ratio will either have to be stretched or cropped to fit or will have black bars at the sides or top and bottom.
This refers to the means by which you connect your source (i.e.
set-top box, game console, Blu-ray player etc.) to your projector. The most basic video connections are composite and s-video which are found on older video sources such as VCRs but are not capable of displaying high definition video. For HD you will need an HDMI (High Definition Multimedia Interface) cable. If you also want to connect your computer to a projector, look out for a projector with a VGA connector. Some projectors now also feature wireless connections via smartphone apps allowing pictures and presentations to be displayed on your projector.
Lamp life, usually between 2000 and 4000 hours, is the length of time that it takes your projector’s lamp to reduce to half of its original brightness. As with any light bulb, your projector’s lamp may fail before this time and but may also significantly outlast it. A replacement lamp will cost you between Ł100 and Ł250 and you can significantly increase the life of your lamp by cleaning the projector’s filters regularly, using an “eco” mode (if your projector has one) and making sure that you don’t remove power from the projector before it has properly switched off (i.e. if the fans are still running).
There are two main technologies used in projectors: LCD (liquid crystal display) and DLP (digital light processing). Each has its own advantages and disadvantages. LCD is renowned for having truer colours and better contrast ratio but suffers from a ‘chicken wire’ effect due to small gaps between pixels. DLP has a chip covered in many thousands of tiny mirrors, one for each pixel. This
reduces the chicken wire effect but some DLP projectors cause a visual phenomenon called the ‘rainbow effect’ which some viewers find uncomfortable. There is one other technology used in projectors: LCoS (Liquid Crystal on Silicon) which is a hybrid of DLP and LCD, as it is a reflective technology like DLP but uses liquid crystals instead of mirrors. Sony’s SXRD (Silicon X-tal Reflective Display) and JVC’s D-ILA (Digital Direct Drive Image Light Amplifier) are versions of LCoS technology.
is simply the ability to make the projected image bigger
or smaller to ensure it fits in the area you want.
ideal place to position a projector for the best quality
image is perpendicular to the centre of the screen, but
this is not usually a practical option. Some projectors
are equipped with lens shift, which allows the image to be
moved up and down and side to side. This gives much more
flexibility with the positioning of the projector without
reducing image quality. We would recommend any projector
you buy should have lens shift.
you can't point your projector straight at the screen then
the projected image will not be square. A projector with keystone correction
allows you to squeeze or stretch the image at the top or
bottom or the sides to make it appear square. This also
means that the image is being intentionally distorted and
so will have an effect on the quality of the projected
Most currently available home cinema projectors can display 3D video and the big screen is the best way to immerse yourself in a stunning multi-dimensional viewing experience, whether watching a movie or playing a video game.
However, the recent resurgence of 3D technology and
content seems to be reducing again: it is hampered by a number of drawbacks such as the need to wear glasses, the discomfort and headaches some people experience when viewing.
However, if you want to watch 3D films or play 3D games, a projector is the best way to go.