If you want to transform your living room into a state of the art home cinema,
there are a number of important factors to consider. Most projectors are capable
of taking inputs from both a PC and video sources, such as a DVD player or
tuner box. However, most are also optimised either for PC use or for home cinema.
Very few truly excel at both.
Here are the questions you should be asking yourself when picking your first home cinema projector.
Screen size
This is probably the most important place
to start, as if your preferred projector can't produce the right size image for your room you
can eliminate it from your shortlist straight away. For help on
screen sizes, please call us with the dimensions
of your room, and we'll check the screen size for you.
Brightness
A projector can only add brightness to the surface it's
projecting on to - it can't darken it, so the blacks in the projected
image can be no darker than the screen surface when the projector is
turned off. Ideally you want to set up your home cinema in a room where
you can keep the ambient light low.
We don't generally recommend home cinema projectors for viewing during
the daytime unless you can block sunlight from coming into the room.
Projector brightness is measured in ANSI lumens. Home cinema projectors
are typically rated between 600 and 2000 lumens.
If you have very low ambient light or complete darkness…
In very dim light settings, you can get away with a projector with a
low ANSI lumens rating. As a guide, 700 to 1100 lumens is generally suitable.
You may even find that projectors with more than 1800 lumens are too
bright for watching an entire movie.
If the light in your room will vary…
Perhaps you have a room where you can block out the light, but sometimes want to
put the lights on (you may want to eat your dinner while you're watching 'Alien'?).
In this case, you would be best off choosing a bright projector (e.g. 1400 to 2000 lumens)
which has a low power mode (also known as 'eco' or 'conservation' mode) so you
can drop the brightness of the projector when the lights are off.
If you can't control the ambient light…
If you've got a lot of ambient light in the room and can't do anything about it,
you could opt for a high brightness, high contrast projector. In really bright
conditions, though, we would recommend you opt for a plasma screen instead, as plasmas
are less affected by light. See our sister web site Plasma Point for prices and advice
on plasma screens.
Contrast
Contrast is also a major factor in choosing a home cinema projector. It is measured as a
'contrast ratio', e.g. 400:1. This tells you the difference in brightness between a
'fully on' pixel and a 'fully off' pixel. For instance, on a projector with a 400:1
contrast ratio, and (for simplicity's sake) a 400 lumen brightness rating, 'fully off'
pixels would actually be 1 lumen in brightness.
(Incidentally, you may be wondering why a 'fully off' pixel has any brightness at all.
Unfortunately there is some 'leaking' of light with all projectors which means black is
not actually pitch black, which is why we keep putting quotation marks around 'fully off'!).
So that's the technical explanation over. What does contrast actually mean to you?
Essentially, the higher contrast on a projector increases the perception of depth in the image, and means
subtle colour variations show up more clearly. Hence subtle textures are more visible. It also means
that dark scenes don't look washed out. Visualise, for instance, the space battles in Star Wars where
the backdrop is a bit grey, and you understand the need for a higher contrast projector.
LCD or DLP?
There's been a long running battle between LCD (liquid crystal display) and DLP
(digital light processing) technologies. Both have merits for home cinema.
Here's a brief summary.
| LCD |
DLP |
| No rainbow effect |
Rainbow effect experienced by small proportion of users. Virtually eliminated with new DDR chip. |
| Slightly more saturated colours |
Less saturated colours, but improving significantly, especially with new DDR chip. |
| Generally lower contrast ratios up to 800:1 (at time of writing) |
Higher contrast ratios up to 3000:1 |
| Small gap between pixels, resulting in slight 'screen door' or 'chicken wire' effect. |
Much smaller gap between pixels, resulting in smoother overall image |
| Small possibility of dead pixels |
Dead pixels virtually non-existent |
In most cases we would recommend DLP over LCD for home cinema, and this tends to
be the growing consensus amongst other projector experts. Hoewver, if you are
considering buying a DLP projector that does not feature the DDR chip, we
recommend you view the projector (or another non-DDR DLP projector) beforehand to
check if you experience the rainbow effect.
What about CRT projectors?
You've probably seen a CRT projector in your local pub. No doubt it's a
huge box with three different coloured lenses on the front, and you can see a
dip in the ceiling around it where the masonry is starting to struggle with the weight.
While traditionally CRT produced better video images than LCD or DLP projectors,
the latter have progressed so much recently that it's arguable whether CRT still
has an edge. CRT projectors also require calibration, a lot of maintenance, and are
comparatively very expensive. The reason why you still see them in a lot of pubs is
because they are not as affected by cigarette smoke as LCD projectors, so they last
longer in these environments. However, we now have some non-CRT projectors available
which have sealed optics, so are suitable for smoky environments.
Connectivity
Nearly all of the projectors we sell come with the following 'essential' connections:
- VGA (for connecting a PC)
- S-Video
- Composite
DVI and component connections are less common. If you have a high-end DVD player which has component output capability, you can take advantage of these connections so look out for them in the product specification sheets. If you don't have component outputs you can normally use the S-Video connection.
See our Connections article for more information on this subject.
Aspect Ratio
Most projectors have a native 4:3 aspect ratio, which means the height of the projected
image is three quarters of the width. This is the aspect ratio that normal TV
pictures are broadcast in, and computers use.
Recently more projectors have been released with a native 16:9 aspect ratio, which is more
effective for displaying widescreen signals.
What does 'native' aspect ratio mean?
'Native' means that this is the aspect ratio that the projector displays when
you use its entire array of pixels.
It's a common misconception that this means a native 4:3 projector, for example,
can only project 4:3 signals, or that it stretches widescreen signals. In fact most
native 4:3 projectors are '16:9 compatible', which means the projector will display a
widescreen signal by cropping the top and bottom of the image. Similarly, a native 16:9
projector can crop the left and right of the image to display a 4:3 signal.
So which aspect ratio do I need?
Both are acceptable for home cinema, however your preference should depend on whether
you'll be using the projector to purely watch movies or whether you'll also watch a
lot of television or use a PC with it.
If it's purely movies you're after, a 16:9 projector is the obvious choice.
If it's a combination of TV, movies and/or PC use, go for an XGA resolution 4:3 projector.
If you're using the projector for almost entirely TV use, opt for an SVGA 4:3 projector
(or XGA if you have the budget).
Progressive Scan
Most TV signals are sent in an "Interlaced Scan" format. First the display device (TV or projector)
displays the image's odd lines, one at a time from top to bottom. This takes about one
sixtieth of a second. It then fills in the even lines, taking another one sixtieth of a second.
So the full picture is first drawn with half its information missing, which is then filled in.
In all the process takes 1/30 of a second per complete frame.
A Progressive Scan converter takes an Interlaced Scan formatted signal, and converts it to
a superior signal where the complete picture is drawn from top to bottom in one pass. This
results in less flicker and smoother motion.
Some DVD players have progressive scan converters built in, and may have the option
to output in either progressive or interlaced scan modes. Some projectors (in particular
the specialist home cinema projectors) also have progressive scan converters built in.
Alternatively, it is possible to purchase an inexpensive progressive scan converter as a
separate unit which can convert your TV and DVD signals.
Resolution
When looking through the specifications of projectors available at Projectors UK,
you'll notice they're generally classified as having either SVGA or XGA resolution.
The resolution you opt for determines how many pixels the projector can display at one
time, which in turn affects the smoothness of the image.
XGA resolution is inherently superior to SVGA, as it displays about 63% more pixels.
Of course, this also means it's more expensive.
However, just because it's better it doesn't mean you need it. Its main advantages
for home cinema are that it will fair better with high definition pictures (eg. HDTV, DVD),
and do a better job of displaying a 16:9 aspect ratio image on a native 4:3 projector (see
the section above on aspect ratios). But if you're on a budget, SVGA resolution is still
pretty good for video images, as video signals (particularly TV signals) don't tend to be
all that finely detailed, and so there's only a small benefit to having a projector with
higher sharpness capabilities than your signal can provide.
See our article 'Projector Resolution' for more information on this subject.
HDTV compatibility
Although High Definition Television (HDTV) isn't a
standard yet, it should be a consideration if you're
investing in a projector for the long term. Check the projector
brochure for HDTV compatibility.
Bulb life
You might have noticed how expensive replacement bulbs are for projectors. With
this in mind, a long bulb life is a definite advantage.
2000 hours is about average. Some projectors go up to 6000 hours. With a lamp
module costing about £350, a 2000 hour bulb works out under 20p an hour of usage,
which certainly beats going to the cinema, but may be a price consideration.
We should also stress that bulb lives quoted are typical and there does tend to be
variation in how long they last.
Still confused?
If you need help, we're here to deliver it. Just give us a call for expert advice on
choosing a home cinema projector that's right for you.
