A few questions about image brightness for large (150") screens - AVS Forum
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post #1 of 7 Old 12-04-2012, 01:02 PM - Thread Starter
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Hi all. I am coming up on 1 year of using an Epson 8350 to power my 150" screen in my dedicated home theater room (fully light controlled). I am considering upgrading in the near future, but I have a few questions that I can't quite figure out from reading existing topics.

When it comes to having "enough" brightness for a 150" screen, how do you determine this? My projector currently sits about 12.5' from the screen and thus I am zoomed all the way to telephoto on the lens' 2.1x zoom. Now I know this closes down the iris some and costs me some brightness, but I also know that distance from the screen costs you brightness as well. So would it be brighter to fill a 150" screen zoomed to 1x on the lens but 20+ feet away, or 2.1x zoomed and only 12 or so feet away?

Secondly, unfortunately for me I cannot stand the sound of my epson 8350 on high powered lamp mode. The higher fan speeds being louder are less ideal, but I could live with that since it is constant. What I cant stand is that there is this pulsing noise that is higher pitched that accompanies the increased fan speeds that is absolutely not there in ECO mode. So while I think I prefer the brightness overall for movies in High lamp mode (using cinema preset with calibration tweaks), I just can't stand the droning audio pulse noise, so I am losing even a bit more brightness from ECO mode.

That said, how bright is bright enough? I can't really tell how to measure footcandles etc (although I do have a lightmeter app installed on my iPhone that I BELIEVE is giving me a footcandles reading of about 7 or 8 in my current setup). I know this stuff is all subjective and eye of the beholder, but regarding an ideal or attempted objective calibration, what should I be shooting for and what can I hope to achieve in brightness if I make a projector upgrade? I think my setup could benefit from some added brightness (such as slightly prefering the look of High lamp over ECO mode on my 8350), but in general bright daylight scenes are fairly bright even as is.

The model I am leaning heavily towards is the JVC x30 for what appears to be a much higher 2d lumen value in its best mode (which I am unsure if this is eco or high powered lamp) while maintaining a near silent audible operating sound level and great black levels/contrast. I am also considering the panny ae8000 and the epson 5020ub, but I am concerned with both the epson and panny that they wont be much brighter in best modes, and if I run high lamp mode, I may not be able to stand the increase audio sound levels (it all depends on how it actually sounds I suppose).

Any information on this would be greatly appreciated, as to how people make determinations on brightness per screen size per distance from screen per lens zoom per lamp lumens, etc lol. Thanks so much for any input!

(side note, I created a custom painted screen at close to 1.0 gain. I started with a slightly glossy satin finish pure white paint from sherman-williams, but there was always hot spotting on bright scenes and I couldn't accept that tradeoff for a slight brightness boost over a more matte finish)
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post #2 of 7 Old 12-04-2012, 01:25 PM
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Any chance you can mount your projector just behind your view area about 12" over your seated eye level and upgrade your screen to a Dalite HP.?

Here is a glowing review of someone with a 159" HP ..
http://www.avsforum.com/t/1438322/love-my-new-2-4-gain-high-power-screen-mini-review/0_100#post_22589031

Doug

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post #3 of 7 Old 12-04-2012, 01:47 PM
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Quote:
Originally Posted by airscapes View Post

Any chance you can mount your projector just behind your view area about 12" over your seated eye level and upgrade your screen to a Dalite HP.?
Here is a glowing review of someone with a 159" HP ..
http://www.avsforum.com/t/1438322/love-my-new-2-4-gain-high-power-screen-mini-review/0_100#post_22589031

I second this. I love my 135" HP screen with my Epson 6010. I can run it on eco mode with the contrast cranked down to -10. If your room allows, it is something you should consider.
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post #4 of 7 Old 12-05-2012, 07:00 AM - Thread Starter
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Question about high gain screens, won't the exhibit hot spotting? With the mildly glossy paint, there was a pretty distracting glare present on the screen whenever the scene had a decent amount of brightness to it.
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post #5 of 7 Old 12-05-2012, 07:08 AM
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Quote:
Originally Posted by allupons View Post

Question about high gain screens, won't the exhibit hot spotting? With the mildly glossy paint, there was a pretty distracting glare present on the screen whenever the scene had a decent amount of brightness to it.

This is not paint. There are many threads in the screen forum about the HP screen. The surface is covered with billions of micro beads that reflect the light back to the projector, hence the need for the near eye level projector placement for the maximum gain. It does NOT hot spot. You will find many many many fans of the screen in the screen forum, especially those with very large screens like you have. I would suggest spending some time doing a search of that forum for HP and read what has been written over the years. The current version is 2.4 gain and is somewhat different than the original 2.8 gain. However these differences seem to be improvements with the reduction of red push and higher gain of off axis viewing but a slightly lower max gain.

Doug

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post #6 of 7 Old 12-06-2012, 06:22 AM - Thread Starter
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Thanks for the feedback. I will check into the high gain screens more for certain.

Regarding the other questions, can anyone give feedback on the issue of brightness loss from the projector being at a greater distance vs brightness loss from being closer to the screen but with a 2.1x zoom having the aperture close down?

Also, is there some sort of standard as to how bright is bright enough? And if so, how do people get the measurements so that they know if they are falling inside of that range? Thanks for any help.
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post #7 of 7 Old 12-06-2012, 07:02 AM
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12-16 fl (foot lamberts) for front projection in a dark room. Typically a special meter is use with calibration software.
No idea on the zoom but is not going to be day and night different.. I recall reading some other posts in the past where the poster moved his projector form 20 back to much closer and saw little change. I would suggest as you research the HP screen, you call Dalite and ask them to send you samples, it is free and you will be able to compare the brightness to your current screen however you will have to compare while standing under your projector at the projected level you intended to move your projector to. I.E. if you will have the projector 12" above your seated level then that is where your head will need to be while comparing the sample to your screen.

Doug

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