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Originally Posted by pfil Hey Chernobyl, I've been lurking in the forum a week or two. Love what you're doing. Can't wait to see what your MH lamp does as I'm going to try it as soon as you post your results assuming they are favorable. I got a 4000 lumen projector and am waiting for a good deal on LCD's on ebay.
That said, I got a crazy idea, I'll see what everyone thinks. What if I got 2 of the exact same lcd and stacked one on top of the other to try and improve contrast ratio? I'm sure blacks would be blacker and of course you'd block twice as much light, needing even more lumens but assuming you lined everything up perfectly and avoided parallax, would the colors and whites be OK? Any thoughts? It appears you can easily get a projector with the same specs as a high end projector with XGA resolution and high lumens but I've seen projectors with 2000:1 contrast ratio, most lcd's I find or 400:1 or so with expensive one's being 1000:1. No 2000:1 monitors. |
Hi pfil
Welcome to AOA on behalf of the cool chaps who run this site.
Thanks for joining in, great to have you here.
I cant wait for the MH bulb
, I hope it really does more or less drop in.
Hehe, your crazy idea has been discussed in a few places but unfortunately wont give a good result. I'll explain as best I can...
When an LCD passes light with no filter, there will be losses in the light power.
To pass white light in a colour LCD, Red Green and Blue colour filtered Liquid crystals are used. Each one can only pass the one colour in different brightness levels.
To produce 1 white pixel, a red, green and blue pixel are needed.
Each of these coloured pixels blocks 2/3rds of the light, so immediately just passing through the filters, you have lost 66% of the light.
The LCD is coated on at least one face with a polarising filter. Losses will occur travelling through both the LCD and the filter(s).
Not all the light hits the LCD crystals, there is a tiny space between each one which will also block light.
There is a coating thats helps light dispersion too which will reduce light power (I just read you post Gizmo, thanks for the reminder
)
Any light absorbed by the LCD panel would be converted to heat.
I estimate that the max light that an LCD will pass is somewhere between 10% and 20%. Stacking 2 high would give you only 15%ish of the light you have with 1 LCD.
Its nice you are thinking about ways to help this though, keep it flowing