Help! 7 lux @ 5m on a 140" screen enough for a JVCX9? - AVS Forum
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post #1 of 6 Old 08-15-2012, 03:54 AM - Thread Starter
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I need help! Please...

I have decided to buy a JVCX9/60 but some forum members warned me against its poor light output. So I decided to measure what I have today and ask for advice because, today, I find my setup too dark and I would like to improve it with the X9. If the X9 will leave things unaltered (or worsened) then I cannot buy this projector.

Room: completely dark but has white walls and ceiling
pj: Yamaha DPX1200 lamp set to max brightness
screen: 140" Kikuchi KSL 16:9
screen lens distance: 5m
screen eyes distance: 4.8m
room size: 17.5m2 (4.9x3.6.2.8m)

I hope that I measure luminance correctly:
- luminance measured where the focusing pattern green lines intersect (cross): 7 Lux
- luminance measured where my eyes are: too low - outside my instrument's scale.
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post #2 of 6 Old 08-15-2012, 04:23 AM - Thread Starter
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Sorry, I need to correct these values with full white screen:

I read 28lux right in the middle of my screen and a bit less (27/26) at the far corners.
Were I sit I read 3 or 4 Lux depending on where I sit.

I find this not sufficient for my liking.
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post #3 of 6 Old 08-15-2012, 06:02 AM
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28 lux...

That's an extremely low number...

That's around 2.6 ftL.

How are you even watching the thing...

You will want minimum 5ftL and that is still extremely low.

12 - 16ftL is recommended.

What gain is your screen?
What is the lumen output of the X9 if you know it?
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post #4 of 6 Old 08-15-2012, 07:31 AM
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Quote:
Originally Posted by ascanio1 View Post

Sorry, I need to correct these values with full white screen:
I read 28lux right in the middle of my screen and a bit less (27/26) at the far corners.
Were I sit I read 3 or 4 Lux depending on where I sit.
I find this not sufficient for my liking.

Are you placing the light meter directly in front ot the screen and pointing the light meter's pickup back toward the projector? That is the correct method and you will get low (and invalid) readings if you are trying to measure the lux reading of the light reflected off of the screen (it appears likely this is what you were doing).

With a JVC X9 and when using the correct measurement technique you should get a 100+ lux reading taken directly in front of the center of your 140" screen when operating the X9 in high lamp mode, with the manual iris set for max. light output and when displaying a 100% white test pattern with the projector mounted at short-to-mid throw distance. Note that the screen-to-projector throw distance (i.e., which impacts where you set the projector's zoom lens) will also impact the projectors light ouput. When the zoom is set to minimum (for long throw) you will get less light ouput than when the zoom is set to maximum (for short throw).

In any case a 140" (16 x 9) screen is too large for the X9/RS60 when used for 3D unless you use a high gain screen, such as the Da-Lite High Power (which requires the projector be mounted near eye level to provide max. gain). The X9 should put out about 600 lumens in calibrated mode with a fairly new lamp. Note that the newer JVCs (e.g., X30, X70, X90, RS45, RS55, or RS65) and the X3/RS40 are typically capable of putting out 800 to 900 lumens in calibrated mode with a relatively new lamp. The lower lumens with last year's X7 and X9 (RS50 and RS60) was due to internal hardware differences as compared to the newer models.
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post #5 of 6 Old 08-15-2012, 11:07 AM
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Those numbers just doesn't seem right
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post #6 of 6 Old 08-16-2012, 06:58 PM
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You should also look at the EH-R4000 or EHTW8000W. You can see these at Bic Camera or Yamada Denki in Japan. I'm also in Japan, so let me know what you find.

Click the link to see pics of my home theater

http://s450.photobucket.com/albums/q...oom/?start=all
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