Overhead lcd panel colors

Hi i have polaroid polaview 1800 lcd panel. And a 400watt a+k ohp. Now when i project my image on the wall the colors seem more or less washed out. Red isn't as red as on my computer, yellow isn't as yellow and so on. If i turn my lcd panels brightness to somewhat darker it seems to show my colors quite a bit better, but my image doesn't get any brighter and get's harder to see. So does anybody have a solution? I was thinking of modding my ohp with some kind of bulb, but i don't now what color temperature is needed for the best crispy looking projection. And there is a second problem, i can't find any good MH bulb dealers here in holland. Does anybody have some tips or hints for these questions/problems?


2001-12-20 5:10 am
is it a 400w 36v halogen bulb? Then color temp supposely isn't more than 3600k.Good color temp would be around 6500k, which can't be reached with halogens. With halogens usually the image looks a little more reddish. Maybe you could try a gain screen which can improve image a lot! You loose some of viewing angle but brightness and contrast will be much better. You have the options of retroreflective screens or angular reflective screens. Retroreflective screens are recommended for table type projectors, angular reflective ones for ceiling mounted projectors. I would check this out first before fiddling around with MH bulb replacements !


i have a question about a lcd ...

Which adjustments do i have to make before i can use a lcd screen (5") in my projector ???

Do i have to to remove the back.... and tape a fresnel lens behind it???

Or do i have to completly remove back + backlights?????

PLEASE...help me

thx thx thx .....etc


2001-12-20 5:10 am
my native language isn't english too! I try it anyway:
If you have a white matte screen (white wall, canvas..), the screen gain is about 1,0. Viewing angle is 180° , which means you can look at the projected image from all viewing points without loosing brightness.
If you have screen surfaces which reflect light more than a matte screen, you will have more direct reflections similar to a mirror. That means: angle of incidence = angle of output. Depending of the screen material this gives an increase of brightness within a limited area called viewing angle. Now the reflected brightness of a screen has more gain. There are gain screens from 1,2 up to 16. Screen gain is a ratio factor always compared to a 1,0 gain matte white surface. Most screen gains commonly range between 1,3 and 2,8.
Screens with more gain tend to 'hot spotting', which means some areas of the image are brighter than others. This depends of viewers position in the room in relation to projectors position.
Simple said: A gain screen cannot produce more brightness than a projector gives, but it can collimate the given brightness to the viewer, which now must sit in the view angle area.
Retrofeflective screens are directing light rays back to the lightsource (projector), the same principle like 'cat eyes' in road marking elements.
For more information you should look at 'Dalite' homepage.There must be somthing like 'educational', which gives an overview of all types of screens.

Good luck!
i think something you all overlooked here is contrast.

colors look vibrant and bright becuase of those factors you mentioned, but also because of contrast. many panels have VERY VERY low contrast ratios, giving dull or washed out images. your monitor has like 2000:1, your panel has like 100:1.

the ratio from what i understand is the on/off ratio. the intensity from full on, to full off. whatever that means :)

but, a screen can fix a lot of that. i have a dalite glass bead screen. and my contrast is only 150:1, and it looks great for movies and high color.
Re: hmzz

personally i would recommend buying a screen. you can get a brand new dalite here in the states for around $80 for a 60"

and there are also many ways to build a screen. i have tutorials on my site, which is of course down. but the links are on my computer at home (im at work now). i can post them when i get home.

daburnd88 said:
what kind of stuff to make a screen of would u recommend or is it a better idea to buy a real beamer screen?