DIY Video Projector - Page 268

Marklar · 23rd June 2002, 11:05 PM

Is this good enough for you?
Check out www.hommie.net for the full story. OMG im so happy all i need is a peice of Low-e glass the put in front of the bulb and a vent hole in the top.

noodles · 23rd June 2002, 11:05 PM

Shame on you if anyone here hasn't been to his site.

Where can I get Low E glass? How much does it cost? My OHP is getting up to 125 degrees F

thelaw · 24th June 2002, 12:36 AM

Marklar: Is your OHP's fresnel glass or plastic?

cheers,

xblocker · 24th June 2002, 01:42 AM

woneill,
projectors contrast in first instance is the the ability of a image source, LCD, slide, film, dmd to block out light, the ratio between the brightest parts (full transparency, full reflection) and the darkest parts (blockout, black). There's no way to eliminate poor contrast with a lens !
If the lighting path matches the image path optimally, it's only image source which determines contrast ratio. You can look at all kind of projectors, there doesnt exist a 'contrast' lens.
Of course there may be some points, where scattering light can decrease contrast. This even is the case with DLP projectors, when micromirrors are bouncing light internal when turning to black!
LCD blacks shift to grey due to bad light blocking.
Black can not be projected!!! Black is always the absence of light. So best way to improve contrast is to avoid scattering light as good as possible!

xblocker

fender4 · 24th June 2002, 02:19 AM

Interesting discussion, everyone! I agree that the real value of MLA's is the increased efficiency, which can be quite dramatic. This is part of what allows a projector like this one achieve 3500 ANSI lumens with a 200 watt bulb.

Brainstorm Feel free to shoot this down. I'm just throwing this out. Assuming that monochrome LCD's allow more light transmission because of less TFT's, would it be possible to use a single monochrome LCD in conjunction with a color wheel (like a DLP projector) to take advantage of this? RGB signals could be modulated in synchronization with the rotation of RGB filters in the color wheel. The panel would need to have a fast rise/fall rate to handle the 3 signals. The increase in transmission of light through the LCD might be negated by the filters, but then again, isn't a color pixel just a filter anyway? So, the light gets color filtered and more passes through because of less LCD "guts" blocking/scattering the light.

I just gave myself a headache.

Congrats on your setup, Marklar! It looks like you have a nice picture. Could you take some pictures of a movie or something with some colors? Just curious to see what it can do. Also, has anyone found a price/supplier for Marklar's reflector? Thanks.

-f4

Piston · 24th June 2002, 02:50 AM

Anyone care to give some feedback on this lamp??? still looking for setup price in Canada. the 4000 K +-200K color deviation looks attractive.
http://www.lighting.philips.com/nam/...yhid.php?id=71

xblocker · 24th June 2002, 02:59 AM

fender 4,
for LCDs, it's still too fast, DLPs can handle multiple frame frequencies much better than LCDs can (actually). Another point: DLPs often have not only RGB wheel, but RGBW (W=white) and future DLPs will have RGBRGB, to eliminate RBE, thats the 'rain bow effect'.

xblocker

HokieTT · 24th June 2002, 03:06 AM

Marklar,

The hole on the reflector you have appears to be smaller than the diameter of the bulb's base. How did you modify it to fit? Thanks.

fender4 · 24th June 2002, 03:24 AM

Thanks or the good info, xblocker! I had a feeling it wouldn't be feasable, but at least it got me thinking. That DLP stuff is interesting...too bad it is off the DIY radar.

-f4

xblocker · 24th June 2002, 03:30 AM

Yep!
lately i've seen a brandnew DLP replacement unit on ebay for 40$, but only single DMD chip, without controller, too bad...!

xblocker

23rd June 2002, 11:05 PM	#2671
Marklar diyAudio Member Join Date: Apr 2002 Location: Fort Worth, Texas	Woot Is this good enough for you? Check out www.hommie.net for the full story. OMG im so happy all i need is a peice of Low-e glass the put in front of the bulb and a vent hole in the top.

24th June 2002, 12:36 AM	#2673
thelaw diyAudio Member Join Date: Apr 2002 Location: London	Marklar: Is your OHP's fresnel glass or plastic? cheers, __________________ Jon

24th June 2002, 02:19 AM	#2675
fender4 diyAudio Member Join Date: Dec 2001 Location: USA	On the fringe...thoughts on efficiency. Interesting discussion, everyone! I agree that the real value of MLA's is the increased efficiency, which can be quite dramatic. This is part of what allows a projector like this one achieve 3500 ANSI lumens with a 200 watt bulb. Brainstorm Feel free to shoot this down. I'm just throwing this out. Assuming that monochrome LCD's allow more light transmission because of less TFT's, would it be possible to use a single monochrome LCD in conjunction with a color wheel (like a DLP projector) to take advantage of this? RGB signals could be modulated in synchronization with the rotation of RGB filters in the color wheel. The panel would need to have a fast rise/fall rate to handle the 3 signals. The increase in transmission of light through the LCD might be negated by the filters, but then again, isn't a color pixel just a filter anyway? So, the light gets color filtered and more passes through because of less LCD "guts" blocking/scattering the light. I just gave myself a headache. Congrats on your setup, Marklar! It looks like you have a nice picture. Could you take some pictures of a movie or something with some colors? Just curious to see what it can do. Also, has anyone found a price/supplier for Marklar's reflector? Thanks. -f4

24th June 2002, 03:06 AM	#2678
HokieTT diyAudio Member Join Date: Jun 2002 Location: Blacksburg, VA	Marklar Marklar, The hole on the reflector you have appears to be smaller than the diameter of the bulb's base. How did you modify it to fit? Thanks.

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23rd June 2002, 11:05 PM	#2672
noodles diyAudio Member Join Date: Jun 2002 Location: Gulf Coast, Punk	Shame on you if anyone here hasn't been to his site. Where can I get Low E glass? How much does it cost? My OHP is getting up to 125 degrees F

24th June 2002, 01:42 AM	#2674
xblocker diyAudio Member Join Date: Dec 2001	woneill, projectors contrast in first instance is the the ability of a image source, LCD, slide, film, dmd to block out light, the ratio between the brightest parts (full transparency, full reflection) and the darkest parts (blockout, black). There's no way to eliminate poor contrast with a lens ! If the lighting path matches the image path optimally, it's only image source which determines contrast ratio. You can look at all kind of projectors, there doesnt exist a 'contrast' lens. Of course there may be some points, where scattering light can decrease contrast. This even is the case with DLP projectors, when micromirrors are bouncing light internal when turning to black! LCD blacks shift to grey due to bad light blocking. Black can not be projected!!! Black is always the absence of light. So best way to improve contrast is to avoid scattering light as good as possible! xblocker

24th June 2002, 02:50 AM	#2676
Piston diyAudio Member Join Date: May 2002	Anyone care to give some feedback on this lamp??? still looking for setup price in Canada. the 4000 K +-200K color deviation looks attractive. http://www.lighting.philips.com/nam/...yhid.php?id=71

24th June 2002, 02:59 AM	#2677
xblocker diyAudio Member Join Date: Dec 2001	fender 4, for LCDs, it's still too fast, DLPs can handle multiple frame frequencies much better than LCDs can (actually). Another point: DLPs often have not only RGB wheel, but RGBW (W=white) and future DLPs will have RGBRGB, to eliminate RBE, thats the 'rain bow effect'. xblocker

24th June 2002, 03:24 AM	#2679
fender4 diyAudio Member Join Date: Dec 2001 Location: USA	Thanks or the good info, xblocker! I had a feeling it wouldn't be feasable, but at least it got me thinking. That DLP stuff is interesting...too bad it is off the DIY radar. -f4

24th June 2002, 03:30 AM	#2680
xblocker diyAudio Member Join Date: Dec 2001	Yep! lately i've seen a brandnew DLP replacement unit on ebay for 40$, but only single DMD chip, without controller, too bad...! xblocker

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