Questions & Answers:
Projector Specifics |
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| How bright a projector should I get? |
| Projector brightness is a tricky area. Obviously the larger the ANSI Lumen figure, the brighter the picture is going to be. However, and certainly in the case of Home Cinema, the general trend is the brighter the picture, the more colours are washed out and the more blacks become grey!! For a Home Cinema projector brightness should be around 600-1200 lumens. Some are a little brighter since they have “Lounge Modes”, but they will run at low brightness in Cinema conditions. |
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| How often should I replace the bulb on my projector? |
| A projector’s “Lamp Life” gives an idea of how much usage you will get between bulb changes. This information is available in the manual, and on product specification sheets. To extend the lifetime you could run in low brightness mode, and make sure you follow the correct procedure (as detailed in the manual) for allowing the lamp to cool down after use. Today’s metal halide lamps won’t simply pop and not work anymore, the output of the lamp will begin to deteriorate once it is near the end of it’s life – see here for more information on replacing lamps… |
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| Do I go DLP or LCD? |
| DLP and LCD are the two most common technologies behind digital projectors. LCD has been around for much longer the DLP and as such is available at lower prices with high resolutions. In the sub-£2000 market LCD is King of the Roost with projectors from Panasonic, Sanyo and Epson giving hugely detailed and colourful images – the absolute latest models actually proving to be quite bright under “lounge room” lighting conditions too!
DLP is the superior technology but in terms of resolution for the money is more expensive. However, the colour and contrast of the technology is significantly better – so much so that many Cinemas are now changing over to this technology. To sum up DLP in a sentence – daytime looks like day, nighttime looks like night! Perfect colours without the washed out feel of LCD make daytime scenes feel like you’re looking out of a window (!) and immense contrast ratios mean a DLP projector can happily pick out a black button, on a black lapel, on a black suit, worn in the dark! (Where an LCD projector would just about make out the guy in the suit against the dark background) |
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| What is the “screendoor effect” and what is the “rainbow effect”? |
| This also relates to LCD and DLP technology. In LCD projectors, light is passed through an LCD chip (displaying a tiny version of the picture) and then zoomed up onto the screen. Where dark areas border the pixels there is a “chicken wire” or “screendoor” grid pattern on the screen. This is only noticeable up close, but on older lower resolution (hence bigger pixel) projectors this was quite a problem.
DLP technology is based on reflecting light off a chip rather than transmitting through one, this means far less pronounced gaps between pixels and hence no “screendoor”. However, with the large cost of DLP chips, manufacturers cannot afford to install one for each colour (red, green and blue) in order to project all three primary colour images over one another as they do in LCD projectors. Instead all light is passed through a colour wheel that has these three colours as sections on the wheel and the single chip beams the same image three times – once for each colour. (Confused yet???)
The rainbow effect occurs when you dart your eyes quickly across the screen (can happen when you are sitting too close to a large screen and the action moves swiftly from side to side, or more commonly when you’re not really looking at the image and you catch a glimpse of something quickly). When this happens your eyes see all three colour streams as a mini rainbow across the light beam from the projector! Many people quickly adjust to this once they have installed their DLP projector but some are more susceptible than others. For an interesting article on the rainbow effect click here
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| What type of projection screen material should I use? |
| Asides from specific requirements such as rear projection systems or having acoustically transparent screens there are two main schools of thought on projection materials with the aim of getting blacks as dark as possible. The first is to go for a gain of around 0.9-1.4 (1.4 gain means 1.4 times the amount of light projected is reflected back at the viewer) and limit as much as possible the amount of ambient light in the room. With today’s projectors it is relatively easy to achieve a very good picture this way using blackout blinds and turning off all the lights, maybe decorating the room in a dark blue or black colour.
The second approach is to go for a gain of below 0.9, which will produce a dark picture giving good blacks but now causing whites to appear grey. If you can setup up your projector successfully using a combination of significantly higher than usual light output and incredibly low gain screen you can realise a fantastic picture of jet-black blacks and awesome white – however realistically this has never been properly achieved!!!! 9 times out of 10 we recommend going the 1.1 gain route and blacking out your windows. |
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| How big should my projection screen be, and how far away should the projector go? |
| Generally speaking your viewing distance should be a minimum 1.5 times the width of your screen i.e. you should be looking at an 8’ wide screen from at least 12 away. Projector Central has a very interesting article on this subject |
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