CurtPalme.com Home Theater Forum

[Bitwize]

How many foot lamberts do you all shoot for with your CRT PJs?
Also, what foot lamberts are you G70 owners getting these days?

Thanks!

[Clarence]

Depends mainly on the size of the screen. If the tube output is set up properly, you'll probably get about 7-8 FtL on a 7-8' wide screen, 5 FtL on a 9' wide screen.

[Bitwize]

to what screen gain would that apply? i'm using a 1.4 gain screen, but i'm thinking it's actually closer to 1.1-1.2.

[Clarence]

The 7-8 ftL range already accounts for a typical 1.0-1.3 gain screen.

[Phil Smith]

I've never understood the fascination with projector output. I mean, it's not something that's adjustable. You set your PJ up properly, and it's either bright enough for you, or it's not.

I never once thought about measuring my G70's output. I never could see the point.

[Bitwize]

Clarence, thanks for answering my questions!

Somewhere on this forum I read that 12-14 foot lamberts was what CRT owners crave. Does that mean 12-14 is very uncommon for a CRT and is only what they wish for? Do most people only get 5-8? Is a higher gain screen a good option for a G70VR or should I stick with 1.1-1.4?

I'm currently getting 12-13 foot lamberts with my G70VR on an 80" diagonal, 1:78 screen that has a 1.4 gain (supposedly).

[Nashou66]

When I run my single marquee i get around 7 but with the tack its closer to 11 and that is a big difference when you see it. Hard to go back to a single PJ after stacking.

Athanasios

[Bitwize]

[Bitwize]

[Phil Smith]

[Bitwize]

[ecrabb]

[Phil Smith]

[AFryia]

[kal]

Nobody's mentioned the most important factor here: With CRT displays the ftL output depends on the white window size. So while my projector does a good 12-13 ftL when displaying a 100 IRE white widow that only uses 10% of the screen, it drops to only 3 or 4 ftL (I'm guessing) when it's an entire screen of white.

So saying you get "X" foot lambers with a CRT projector is absolutely meaningless unless you also mention what sort of test pattern you were viewing. Someone could say they're getting 15 ftL while someone else says they're getting 4 ftL and they both have the same identical CRT projector set up the same way with the same screen. All that's different is the pattern they're using to measure ftL.

See the "Greyscale & colour Calibration" guide in my signature for more information on this and what you should be targeting for good/reasonable image quality, and how CRT differs from the other display devices.

Kal

[kal]

Nobody's mentioned the most important factor here: With CRT displays the ftL output depends on the white window size. So while my projector does a good 12-13 ftL when displaying a 100 IRE white widow that only uses 10% of the screen, it drops to only 3 or 4 ftL (I'm guessing) when it's an entire screen of white.

So saying you get "X" foot lambers with a CRT projector is absolutely meaningless unless you also mention what sort of test pattern you were viewing. Someone could say they're getting 15 ftL while someone else says they're getting 4 ftL and they both have the same identical CRT projector set up the same way with the same screen. All that's different is the pattern they're using to measure ftL.

See the "Greyscale & colour Calibration" guide in my signature for more information on this and what you should be targeting for good/reasonable image quality, and how CRT differs from the other display devices.

Kal

[ecrabb]

Kal, give me some credit, here! I said, "my G70 is putting out just under 350 lumens in the 100% white window"... You were supposed to read my mind and KNOW I was talking about DVE HD Basics. Seriously, I meant to put that in my post, but forgot it. I'll edit that.

You're exactly right, though... Talking about light output without specifying pattern and screen size is like quoting amplifier output power, but not mentioning whether you were talking about a 1khz sine wive, pink noise, etc. and whether it was into a 4-ohm load or an 8-ohm load.

Whenever we talk about reflected light, we should give the full details. Just like an amplifier spec says "300w @ 4-ohms, .05% THD, 1khz sine wave, both channels driven", we should say something like, "My G70 is reflecting 12fL from my 1.24 gain 96"x54" Wilsonart DW laminate screen, using the DVE HD Basics 100% window."

EDIT - I edited my post to add your point, Kal. Thanks! I always forget something!

SC

[Gino]

[Bitwize]

Thanks everyone for the helpful posts!

I now have my G70VR reflecting around 12 ft/l on an 80" 1.2 gain screen using the DVE 100% IRE window pattern.

I also readjusted brightness so I am now getting much better shadow detail at the expense of blacks that are not longer absolute. But it's a nice compromise.

Resolution still looks very good as well.

[ecrabb]

[tony359]

CRT are not digital projectors and to correctly measure the FL on the screen (as told: both in full and windows size) I think that a cinema spotmeter is needed. This device can average the FL measurement since in cinema the image are flashing 48 times a second, with black between them. I think that with CRT a similar device is needed.
SMPTE says 16FL for cinema, with 12/22 (if I'm not wrong on 22) allowed. In my personal opinion (I work in cinemas) 16 is the minimum, 18 is better

Ciao
Antonio