Originally Posted by cientos
I am very exited about this screen, since my living room is completely white. However, I have some concerns:
What do we know about the use of lens shift? I am forced to place my projector horizontally off-centered and wonder if this will affect the uniformity of brightness?
Could you try to verify this on the 12th? (I know something has been written in french about this, but I am unable to understand it..
Thanks for your help and looking forward to hearing your opinions after the 12th!
From what I've read, the use of horizontal lens shift is not really advised because as you've suggested, it will affect the uniformity of brightness... (the question is how much? ). I didn't have the chance to ckeck it on the 12th... Sorry but I didn't have time!
So, the 12th June, I was at the house of the screen maker (Laurent) in company of Franck (his associate) and my girlfriend.
I was there a little less than 2 hours. The screen (16/9) was 2m50 wide and the projector was the sony VW1000ES (18000€): 2000 Lumens calibrated.
I was sitting at 3m.
To sum up:
We did a comparison light off, with the daylight screen and without (directly on the white wall). The gain for black and contrast was huge and the daylight made a very good work at controlling the ambient light.
The viewing angle are not so good. Horizontal half gain (60°), at this position I could see clearly that the nearest side of the screen was a lot brighter than the other side... You MUST stay in the middle. Same thing for the vertical position which should be chosen wisely, as well as the projector position and the screen in order to gain the maximal brightness out of the screen. I say this because to get the best brightness, I had to stand up instead of sitting in the couch with the Laurent settings(Half gain vertical: 35°).
I did see a fair amount of sparkles on the white parts of some film scenes. Laurent said it was the fault of the brightness of the projector and it's maybe the case.
I did the math:
Screen (at the demo) with width of 2,50m (16/9): area: 37,85 square feet
And: lumens = (fL*SqFt)/Screen Gain
The projector had 2000Lumens and the screen a gain of 1,4.
fL= Lumens*Screen Gain/ SqFt= 2000*1,4/37,85= 73,97fL in the eyes!!!
It should be 16fL or at least between 12 and 22 to respect the projection standard... From a distance of 4,5m, I almost saw no sparkles anymore.
As we swiched to 3D while sitting closer to the screen (about to 2,50m), with glasses on (and therefore reduced perceived brightness) the sparkles were less noticeable but the 1,4 gain of the screen was greatly appreciated. With 75% loss behing the glasses, we still had 18,49fL of brightness in the eyes: nice!
At the end, we did a test with sun light from the side and the daylight did a great job at conserving a nice picture.
Conclusion: nice looking screen, good properties to preserve contrast and black in a living room with white walls, sparkling exists for bright pictures (maybe due to too much brightness) and poor viewing angle with non homegenous brightness of the screen as I went on the side. I did not however notice a hot spot.