Hot.com.au > Home Cinema Guide
What you should know before you purchase your home cinema equipment - projectors, plasmas or LCDs!
One of the first things to consider when buying a projector is do you need native wide screen.
(16:9 aspect ratio) or 4:3 aspect ratio?
The latest movies and HD TV are all wide screen, or 16:9.
Aspect Ratio Is the ratio between the width and the height of the picture, so a 16:9 is 16 units of width and 9 of height. Most new home cinema projectors, plasmas and LCD screens will be 16:9.
The gray bars are the same!
Really the 7 bars are the same!
The only difference is how YOU perceived the brightness. That's what we mean by "Real World" we don't get carried away with specifications that just add zeros onto suspect readings.
Specifications often have little relationship to what and how people watch and the conditions encountered in the Real World. -- hot.com.au
ANSI is the only fair way to test contrast ratio, an average reading while the projector is showing black and white at the same time as opposed to full on/off. (e.g. 40,000:1 with the Epson TW6100 and 320,000:1 with the Epson TW8100 etc.)
I just had an outing to the "real" cinema (I can't remember the last time I went), my eyes were opened to the technical aspects of film in a way I've never noticed before. It's good news for the home cinema market, as I've been testing a few projectors and watching HD-TV. I found myself doing a comparison between the projectors I've seen and the movie I was watching in the real cinema. The Home Cinema projectors win.
We now see projectors quoting 200,000:1 CR or more but..
Because total black can only happen in a totally dark room, (I have not seen one yet) and I would not want to watch a movie without some background lighting, it's too hard on the eyes!
Some manufacturers have a dollar each way by quoting the text in the above image.
Basically it's rubbish quoting super high contrast ratios unless (a) Tested in a cinema mode and (b) You have a Totally dark room with dark walls and furniture.
Big numbers look great on the box the projector comes in but in the real world you wouldn't use dynamic mode much and you just can't tell.
70mm movie film has a contrast ratio of 1000:1 (often referred to as Dynamic Range) when I was watching black scenes they weren't black, it looked to me like (as far as contrast goes) as if I was watching a 400:1 LCD projector, that is the black seemed about 5% gray. Note the current crop of HD projectors claim well in excess of 10,000:1 - much more than any source material you'll be watching!
- Contrast perception is influenced by the surrounding brightness.
- Brightness is the perception of measurable luminance.
Will you or your audience see DLP Rainbows?
DLP projectors (and indeed TV, Single Chip) flash parts of a colour one after the other to make the illusion of the whole colour (using your eye/brain visual processing) whereas LCD models project all 3 primary colours (RGB) at the same time so the colour projected is the colour you see, they're also vibrant & natural colours.
It's our opinion (not a fact) that people who suffer motion sickness, migraines or are epileptic should consider avoiding single chip DLP. Just an opinion based on our experience. Do some research on flashing lights or strobes as a starting point. Another problem with some DLP projectors is the bearing on the colour wheel becomes noisy and/or fails as it's spinning at a very fast speed.
Most people can see "Rainbows" (RBE) once they know what to look for, put another way they thought the artifacts were normal. Some people knock us (normally forums) for showing this information but they are not in the firing line, they have not had to issue refunds and often they are simply defending their purchase, which is understandable. They can also be people selling just DLP.
Many people love their DLP displays. It depends on how sensitive you are to the sequential (flashing) nature of the system. We got into hot water for even suggesting that people who get motion sickness may be in the group to avoid SC DLP that was an observation based on our experience only.
At the and of the day you make your own decision but ask why so many manufacturers (even ones that were DLP ) now use 3-LCD in their home cinema models.
"..Single chip sequential color projectors (DLP) use a rotating color
wheel that spins at a rapid speed and displays colors
sequentially. For some users this results in images displaying
color break- up or “rainbow effect” which can be annoying and
distract from the viewing experience.."
- In our opinion if you're easily motion sick, have congenital nystagmus or you're sensitive to flashing lights and your budget is under 15K buy a LCD for most applications.
- Our personal experience is people who suffer motion sickness may also be prone to being "DLP sensitive" but this is just our observation only it has no scientific basis.
- Remember it may be a person watching it, not you that has the problem, that's why we don't recommend installing single chip DLP models in a public place.
Visual fatigue in congenital nystagmus caused by viewing images of color sequential projectors (DLP)
Abstract Color breakup is the perceived splitting of the white portions of an image into its red, green, and blue components when the image is projected with the color sequential method and the viewer is moving his or her eyes.
This study aims to evaluate how color breakup affects symptoms of visual fatigue in people with congenital nystagmus. The eyes of people with congenital nystagmus continuously oscillate leading to color breakup without pause. One in every 1500 persons is afflicted with congenital nystagmus. Many sufferers have almost no symptoms in daily life except for a mild deterioration of visual acuity. Five subjects with congenital nystagmus were shown a 15-min portion of a movie projected with three video projectors (one liquid crystal display (LCD) projector and two single-chip digital light processing (DLP) projectors). They were subjectively evaluated both pre- and post-viewing with a questionnaire listing visual fatigue symptoms.
One subject was tested in an additional experiment using six more projectors.
Results indicated that subjects with congenital nystagmus felt severe visual fatigue after they viewed images produced by color sequential projectors. Mechanism of the cause of visual fatigue is not clear in general and in color breakup in congenital nystagmus, however, it was clear that people with nystagmus felt continuing color breakup as a flickering image.
Flickering light is a major cause of visual fatigue.
Color sequential projectors are best avoided in public settings, such as classrooms, lecture theaters and conference sites.
Ogata, M. Ukai, K. Kawai, T.
Sch. of Sci. & Eng., Waseda Univ., Tokyo, Japan;
Source http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1545796 More information
3LCD have "No Color Breakup" or "Rainbows" since this technology simultaneously projects three full-time red, green and blue images, there is no color breakup or " rainbow effect" to potentially cause viewers eyestrain or visual fatigue.
Screen Size, Distance and Type
As a general guide you'd want to be sitting between 3.5 and 5.0m back from a 100 inch screen. 5m to 6m for 110 inch, over 6m 120 inch. Personal preferences plus the position of the projector and it's zoom capabilities may come into play.
It's not only the throw distance that determines the brightness of the image, but the size of the image, if the screen width is doubled the brightness declines by a factor of four.
If you intend viewing in a brightly lit room the projection screen makes the world of difference. The "Daylight" screens are expensive but worth every cent. Nothing works well with sunlight in the room.
Standard Projection screens are normally "Fixed" (like a painting) or "Pull Down" (like a blind). Fixed is better as there are no ripples or distortions.
Actual Image showing the effect ceiling mounted lighting hitting a projection screen can have and how a "Daylight" screen almost eliminates the problem.
How long your projector lamp lasts depends on several factors including:-
- Keeping the fan filter clean Not moving the projector while it's turned on The number of times you turn the projector on and off in a day.
- How much time it's used in "Low Lamp Mode" (more the better) How long you normally use it for (over 4 hours the heat starts to build up)
- Lamp output falls dramatically towards the end of its life. You may want to replace a lamp after 2,000 hours even though it may run for another 1,000 hours.
- You would do this if unhappy with the the lower brightness level and/or don't have a light controlled room.
- Remember most lamps are warranted for 3 months or 500 hours, some like Sanyo may go to 12 months and have pro-rata options.
- If you buy a spare lamp, swap to it ASAP as you must report a Dead On Arrival lamp within 7 days. After your original lamp has done 500HR/ 90 days keep it as a spare and use the new lamp because warranty starts from the time you purchased it, not the date you installed it.
- All lamps have a unique serial number.