Screen Size vs Projector Lumens/Brightness

Thanks, Greg! Very timely for me, as I'll soon be building a riser, adding seating, picking screen and projector... the whole thing.

You da man.

John

Great! Thanks Greg. I'm sure this will become a sticky soon.

Terrific Greg, thanks. I just used it to calculate the JVC RS2 (based on the measured lumens output on your review) on various screen sizes and gain so it was very helpful.

Looking at the numbers, if they are accurate, it would suggest I don't need a 1.4 gain screen to get good brightness at the screen sizes I'm looking at (which are fairly large) and 1.0 gain would be good.

But then I have to remember to account for bulb dimming. I'm supposed to look at numbers on such a calculator and plan for half the brightness (bulb dimming) am I not?

Thanks,

Rich H

Yet another excellent contribution to the community. Thanks, Greg.

Just wanted to say thanks Greg. This is extremely helpful.

This is exactly what I needed. Thanks

excellent initiative
Greg: what ftl does a typical crt tv (you know those 16/9 80cm diag. tv before plasma lcd took over) yield (50FTL ?) ? and what is a bright cinema luminosity in ftl (20FTL ?) ?

thanks.

thanks
oh jeez up to 100FTL tv ?
cinemas: so true.old xenons are so common. (given the cost.... )
myself i much more enjoyed a punchy bright image in my HTheater than a dim 10FTL
but it's still very hard to get unless yr screen is small or the projector able to give 1500-2500 lumens whch still costs a fortune (SIM2/RUNCO)
a bright image gives so much more realism, liveliness.
i just tested again the C3XE and the BENQ W5000 with a scene of IN THE VALLEY OF ELAH when TLJones follows the scop who will arrest that mexican soldier. it's so great to sometimes have pjs able to give decent luminosity (800-1500lumens), helped by screen gain.
but we're still far away from affordable <8K projectors able to give us 1500lumens calibrated. that neverending race towards on/off (neglecting ANSI and brigthness though DLP light path advances have allowed the latest dlp to double or triple their brigthness) is fatiguing.

I always wondered how they measured brightness in theaters when they set the 12-16ftlamberts number. At 12 ft lamberts the resolution of the eye is around 2 arcmin and it improves to 1 arcmin at 100ftlamberts

There was a guy on another forum who new people at lucas's light,sound and magic who said that when they tested and reviewed digital movies they did it at 16 ftlamberts. they also stated that 20 ftlamberts was too bright because it screwed up the Gamma. I believe them but I don't understand the statement unless something is going on with the response of the eye

If you look at the resolution of the eye, with extremely good vision it is only an arcmin at the fovea and at 10 degrees it is down to 6 arcmin. 1 arcmin is 1 mm at 11 feet and this resolution is only achievable under the most favorable conditions. This would imply that , if you even if you assume the most aggressive screen angle +- 20 degrees that 720P should be more than adequate and any resolution above that is overkill but resolution is not the same as edge detection.

Even at 20 degrees, given the illumination law of projectors which dictates a cos to the 4 th falloff, this only gives you a difference in illumination of less then 22 percent and it is gradual. so the only purpose of a curved screen is to eliminate barrel distortion on a 2:35 image. I know going to a 2:35 image really increases my involvement in the image but eliminating barrel distortion may or may not.

Going from 9 to 16 ftlamberts makes a big difference in how how most people perceive the quality of the image. Going higher that 16ftlamberts may be a waste of money.

In a dark room , I think the only thing that matters is subtended angle ,especially if the room is almost black and you have no indication of distance, so get a smaller screen and sit closer. I always thought that sitting 8ft away from a 65 inch plasma screen in a black room may give you the best viewing experience possible at any price for a 16:9 transfer. I wish someone would make a 2:35 plasma screen What is the brightness level of an average plasma and can you turn it down to 16 ftlamberts?

Hi Greg,

Thank you so much for the calculators and the information regarding displays. I have always wondered what a cinema's standard is...12 fL.

Using your calculator based on a RS2@500 Lumens +106" 2.35:1 screen @1.3 gain you get a whopping 23 fL! is this correct or am I doing something stupid? I have attached a screen shot of the calculator.

At 1.0 Gain its 17fL, still far above what you would experience a cinema.

Some people seem to lust after that 'light canon' image, I would just like to replicate cinema conditions as far as possible in my house... I have the RS2, the Prismasonic 1500R, now a just have to choose the screen material for the 2.37:1 screen... seems to be down to the Carada classic white/brilliant white or the Stewart StudioTek G3 as you use... Although the StudioTek is far more expensive!

I assume the gain of the screen at a cinema is 1.0?

Thanks again for all your input on the forums, I have recently subscribed to Widescreen Review after seeing the discussion about your review of RS2.

In my experience you are sort of right about the plasma. I've been a plasma fanatic for many years (have owned one for almost 6 years now) and had planned on upgrading to the Panasonic 65" plasma. I did plenty of experimenting in auditioning that plasma in a fully dark room from various distances. With all the lights off, from about 7 to 8 feet or so it really produced a WOW in terms of vividness, dimensionality and realism that I've never seen bettered. No projector I've seen could "do" what that plasma did
under those conditions (and I watch my plasma in the dark too).

I was able to view the huge Panasonic 103" plasma many times under controlled lighting conditions and it too put out an image that I've never seen matched. There is something to the solidity and realism of the plasma image. For instance, after watching the opening of Star Wars AOTS with it's space battle on a Sony LCD projector (about 103" diag screen) I immediately watched the same scene on a 63" Fujitsu plasma, in the dark. Despite the image being smaller on the plasma, the sense of being in the cockpit of one of the ships speeding around was more intense and I felt more vertigo than on the much bigger projected image.

I've found similar results in playing with projected image sizes, at least in my room with some borrowed projectors. Take the vertigo-inducing end of King Kong in HD, the bi-plane attacks on Kong. I played with very large image sizes from an 11 foot viewing distance, up to 124" wide images. They certainly were immersive. But as I zoomed the image smaller there were gains in image brightness and apparent contrast/punch. As the image got more vivid, despite getting smaller, the "intensity" of the viewing experience seemed to increase, insofar as actually making the image look more dimensional and bringing on the "whoa, I'm in an airplane above the Empire State Building" vibe. So while viewing angle does it's part to a certain degree of making an image convincing and immersive, so does image vividness and sheer size doesn't seem to trump merely on covering more of the viewing angle.

Of course if you can have a really big image with tons of image punch, you get both. That's why the Panasonic 103" plasma no doubt produced the most realistic I-am-there feeling I've ever encountered when watching HD concert footage, HD Nature shows, Blu Ray movies etc.

So why didn't I end up going with the Panasonic 65" plasma instead of going for a projection set up as I am now? Because number one I found I had to do too much re-jigging of my room to get furniture close enough to get that immersive feeling I was craving. A projector
gives that image size/viewing angle effortlessly in my room while keeping furniture in a nice aesthetic arrangement.

Also, while the plasma image is more vivid and intense, it doesn't really fool me into thinking it's actually "big" even when I view it closer.
The space ships in the movie Alien look vivid, but rather toy-sized on a plasma. Whereas at over 10 feet wide on my wall they look HUGE
and much more convincing for it. I find there is only so much you can do to try to fool your brain about image size, and the cinematic quality of a really big image is ultimately more compelling to me.

Unfortunately your right the dam brain is just too good and it picks up distance from the smallest clues and once that happens the illusion is destroyed.

A plasma display, especially a very good one will always be sharper than a projector display because the image is not compromised by a projection lens

One day 10 or 20 years from now, we will be able to paper our walls with a Oled display which has a million to 1 contrast ratio

Greg -

Where did you post the calculator? There was no link or web address in Post #1 and I can't find it on the WSR web site.

Actually I spent time comparing the Panasonic 103" diagonal giganto-plasma with a Sharp Z20000 single chip DLP projector, on the same Blu Ray material. The projector actually seemed a tad sharper than the plasma - the plasma having a bit more "film-like" softness at that size. I suppose processing differences also enter this mix along with lens/no-lens considerations.

"the only purpose of a curved screen is to eliminate barrel distortion on a 2:35 image."

I thought the big reason was so high gain screen material could be used w/o hotspotting

Hi Greg

Can't find link for calculator

Thanks. Got it now.