Hey Everyone. I just recently purchased an Optoma HD70. After searching through countless post on this subject, I could'nt really find a similiar situation as mine. I'm looking for a suitable screen to fit my needs. I will be watching movies only on this PJ through Blu Ray and HD Dvd with HDMI. I would like my screen size to be from 106-120" possibly a little larger. The room will have no ambient light due to night time movie watching only. The room is very large with no surrounding walls near where the screen will be mounted. The projector will be table or shelf mounted. Here are the questions.

1. What is the optimal screen gain for the Optoma HD70?
2. Do I need a white or gray screen?

Any other info you think would be helpful would be GREATLY appreciated.

Thanks in advance.

You are looking for a target brightness of 16fL. (SMPTE)

When properly setup for a theater, the HD70 puts out just under 400 lumens (http://www.projectorcentral.com/optoma_hd70.htm).

If you use a screen with 1.3 gain, you can go to a 106" diag screen (92" wide) and just about reach 16fL.

Lower gain or larger screen will be too dim.

Higher gain screen material would mean you can go a bit bigger but the viewing cone becomes very narrow.

While I don't doubt the above foot-lambert math (I don't understand it, to be honest), I think you'll be fine with either type of screen.

I've watched my HD-32 (Essentially a rebadged HD-70) on a 92" matte white and a 104"(-ish, throw distance wasn't quite enough for 106") matte white. I'm not perfectly light controlled and I still think it looks great.

12ft lamberts is plenty for most people. I would get at least a 1.3 gain screen for 120".

I don't disagree ... I suggest 16fL as a target with a new bulb. Eventually the lamp will dim to 50% (8fL) with the average being 12fL over the lamp life.

This projector doesn't have the poop when calibrated to drive a 1.3 120" screen. You will only get 9.2fL with a brand new bulb! :(

While I don't doubt the above foot-lambert math (I don't understand it, to be honest)The math is simple:

Calibrated projector lumens divided by screen size (in sq ft) multiplied by screen gain.
Calibrated (D65) lumens = 398
106" D screen = 92"W x 52"H = 33 sqft
398 / 33 * 1.3 = 15.6 fL

I don't disagree ... I suggest 16fL as a target with a new bulb. Eventually the lamp will dim to 50% (8fL) with the average being 12fL over the lamp life.

This projector doesn't have the poop when calibrated to drive a 1.3 120" screen. You will only get 9.2fL with a brand new bulb! :(

I have an optoma hd70 and my room is 15x17 walls are beige and my seating distance is 13.5 feet. I have some light from a slider coming in during the day from the right of screen as you look at it. I want 106 inches and am currently using a 100 inch 1.1 gain grey screen. I am looking at the elite cinegrey screens but am not sure if i should go white or grey?
Can you help me?
If i need to I can stay at 100inches.

Can you help me?I'm not sure what your question is.

If your screen is only 1.1 gain, I would not recommend anything larger than a 100"D screen which would provide 14.8fL with a new bulb.

I, personally, prefer the grey screens; I use a Stewart Filmscreen Grayhawk.

Not to be a jerk, buy why buy a 720p projector if you are going to be primarily playing Blue Ray HD? I have a 100" FOCUPIX 1.1 gain and am very pleased with it after previously playing my Panny on a Stewart.

Not to be a jerk, buy why buy a 720p projector if you are going to be primarily playing Blue Ray HD?

Because Blue Ray still looks great at 720p and not everyone can afford 1080p.

I'm not sure what your question is.

If your screen is only 1.1 gain, I would not recommend anything larger than a 100"D screen which would provide 14.8fL with a new bulb.

I, personally, prefer the grey screens; I use a Stewart Filmscreen Grayhawk.

Thank you...would this measurement be with bright mode off on the hd70?
What I am trying to achieve is the largest screen size with the best PQ i can get with this until I purchase a benq 5000. The biggest I could go is 106 inches i think at my seating distance.