AVS Forum banner
Status
Not open for further replies.
1 - 7 of 7 Posts

·
Registered
Joined
·
502 Posts
Discussion Starter · #1 ·
Can anyone make a screen suggestion to achieve 13 foot lamberts (or slightly more) for an NEC XG110 (non lc).

I would like to try for an 87" wide 16:9 screen.

Or am I asking too much from my projector. I'm not sure of the ANSI lumens of this model.

Picture is O.K. on drapery "blackout" material, but not exceptional at 720p


Mooneyass if you read this thanks much for your help last night...I'm finally gettin' there!!!!
 

·
Registered
Joined
·
2,673 Posts
Quote:
Originally posted by hificanuck
Can anyone make a screen suggestion to achieve 13 foot lamberts (or slightly more) for an NEC XG110 (non lc).

I would like to try for an 87" wide 16:9 screen.

Or am I asking too much from my projector. I'm not sure of the ANSI lumens of this model.

Picture is O.K. on drapery "blackout" material, but not exceptional at 720p


Mooneyass if you read this thanks much for your help la


st night...I'm finally gettin' there!!!!
87" x 87" x 9/16 = 4257 square inches, which is

29.6 square feet so you'd need 384 Ansi lumens with a 1.0 gain screen.


However, projectors are rated using the full height of the phospher, so you need to multiple that by 1 1/3 to get what the projector needs to be rated for on a 4:3 screen. Doing that, you end up with 511 ANSI lumens for a 1.0 gain screen.


Divide 511 by the real light output of the projector, and you have the required screen gain to get that brightness (probably 2.something). Conventional wisdom suggests that would be sub-optimal for a flat screen, work OK on a curved screen, and work well on a torus.


Hopefully, some one with practical experience can share their experiences regarding such screens...
 

·
Registered
Joined
·
3,480 Posts
There are some high gain screens out there, but they will work best if curved. Stewart has a 3.2 gain silver screen, $25.00 a square foot. Hurley has a silver screen 2.3 gain $5.00 a square foot. I did a huge DIY curved silver screen that is plenty bright. I like the added size the high gain allows you to have.


Good luck.


Deron
 

·
Registered
Joined
·
502 Posts
Discussion Starter · #4 ·
thanks guys, what you seem to be saying is that it is unreasonable to get the same amount of light output as a theater would give?

Do I need this kind of output? Seems to me that a theater is playing to a larger audience and that may have some factor in perceived brightness. Maybe I'm wrong?
 

·
Registered
Joined
·
226 Posts
Hi hificanuck,


The brighter the better. A brighter picture will look more detailed and colours more saturated. It's like watching a big direct view tube TV especially if you have inky blacks from liquid coupling. What you need is a high gain screen solution without hotspotting or colour shift. Do a search in the screen forum for torus or screen goo.


Ben
 

·
Registered
Joined
·
1,646 Posts
The average picture level of video is around 10%, the Nec Xg-series is rated around 1300 lumen with a 10% area of a 100% ire field, so you should easily do over 10 ft-lambert with at least a 80" wide screen without overdriving your crt's.


The ansi lumen rating is measured with an all white signal and dosen't reflect the performance of a crt-projector for video-content.


Per Johnny Ødegaard
 

·
Registered
Joined
·
2,655 Posts
Hi hificanuck,


I have measured new NEC XG projectors with 20 ft-lambert at center and still below the point of blooming on a 100" wide screen, so much for light output.


So Per Johnny is right, you only have to get a 1.3 gain screen and you'll be all set - even when your projector has several thousand hours more on it, 13 ft-lambert will be easy to get.


I strongly suggest though that you get a color analyzer once in a while to calibrate your greyscale to 6500k and your output to 10 ft-lambert (multiplied with 1.3 gain gives 13 ft-lambert), just so that you get more life out of your tubes and don't start with 20 ft-lamberts and experience an unnecessary decline of output.


Oliver Klohs
 
1 - 7 of 7 Posts
Status
Not open for further replies.
Top