# How bright should a projector be?



## brandonnash (Sep 11, 2006)

On screen, how bright should a projector be? I believe I read one time that most commercial theaters are somewhere around the 15 foot-lamberts area of brightness. I've seen some reviews of home projectors that would measure around 6-7 foot-lamberts on a 100 inch screen. How important is this. I know that most direct view crt tvs are in the 25-45 foot-lambert range. So would this 6-7 be horribly dim even in a cave like dedicated home theater?


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## norpus (Oct 11, 2006)

I have lived with a dim 4-5ftL on an old lamp previously (AE700) but it was really too dim in hindsight
The BenQ 8720 gave 9FtL in low lamp and was very punchy
My JVC HD1 gives 12 on low mode and 15 on high - now that is great
Next stage is to get a 1.3 gain screen to get over 16 which is where I understand is ideal


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## smoov1444 (Feb 10, 2007)

brandonnash said:


> On screen, how bright should a projector be? I believe I read one time that most commercial theaters are somewhere around the 15 foot-lamberts area of brightness. I've seen some reviews of home projectors that would measure around 6-7 foot-lamberts on a 100 inch screen. How important is this. I know that most direct view crt tvs are in the 25-45 foot-lambert range. So would this 6-7 be horribly dim even in a cave like dedicated home theater?


When you speak of brightness, I am of the impression you're referring to brightness coming off the screen. This is where the brightness rating of a given projector really counts. Many installers aim for at least 17, or even 20 foot lamberts coming off the screen.....that is the amount of light reflecting off a screen after the image has been projected. This is what really counts as this will determine how well your image displays. I might add, my reference to front projectors are those in the $15k and up range. These are the star performers. The Infocus SP777, The Sim2 C3X,and The New Sony VPL200 has a 400W halogen bulb and a contrast ratio of 35,000:1(the sony if calibrated correctly should be rather interesting, and it's only $15K.
Hope my note helps.


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## <^..^>Smokey Joe (Jun 29, 2007)

The more you have the more head room for light balance you have. You can actually be too bright aswell where you can cause eye strain. Plasmas and LCD can be like this if your field of view and light levels are not balanced. Try looking into a tourch close up, hurts doesnt it.

For projection systems 12~15ftl is about where to aim for in dark conditions. With a little ambient light the reflective light level needs to get up towards 20fl to not lose infomation within the noise of the ambient light.

Typically 6~12ftl is measured from a medium level calibrated projector. People can go wrong trying to go too big with there screens and sacrifice ftl doing so. What happens here once the bulbs get past 1000hrs they get to dim. Especially in ambient light. 

I use a AE900E, currently up to 1087hrs on the bulb, and I calibrated it last night and got 10ftl. I use a 70inch screen though, but this will allow me to get to 2000hrs. 

It is always a question of balance.


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## Mike P. (Apr 6, 2007)

How do you calibrate it so you know the ftl?


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## <^..^>Smokey Joe (Jun 29, 2007)

A radiospectrometer and the right software reports ftl as part of the outcome.
You could also use a normal photo light meter. Bare in mind most cheap ones only use the Green channel as a sensor. Although in most cases still accurate enough.


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## Rajesh (Jan 2, 2007)

First of all you need to know how dark your room is gonna be while watching a movie. Then, what kind of projector are you looking for ? (dlp/LCD) ? Then comes the ANSI lumen rating of the projector. normally a 1000 ANSI lumen dlp projector is more than enough for a home theater application .

From there you can decide which material screen you want to go for ? (matte white / glass beaded ) ???

Lot of work to do :innocent: 
1. Room size
2. Uncontrolled light
3. angle of viewing
4. projector mounting ? (ceiling/ table top / rear projection )?
5. type of screen ( retro-reflective / angular- reflective )? 
and so on....................


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## Rajesh (Jan 2, 2007)

Foot-Lamberts is nothing but 

ANSI-lumen of the projector _divided by _square foot of the screen .

So you have to decide on the screen size first and then choose a projector..


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