LOL @ fender..hehehehe.....
pinched the camera from work 2 day - i'd post the pics here but my paint crashed and i can't resize 'em
so i put them up on my site.....breakdown is:
2 12v transformers connected in series to give 24v (free)
250w24v stagelight globe (same size as dichroric downlight) (free).....dontcha love friends who are electricians!!!
homemade metal bracket to centre bulb
cardboard length...free (well $20 for the wine holder, i suppose the box was thrown in !)
$3 fresnel
proxima ovation 820c panel 640x480 res, 2 mill colours ($270aust including freight from america)
cardboard box ripped from 100inch tv thingy
another $3 fresnel - these are only temp till i get a glass fresnel and a pcx lens
and....the screen!!! Ansett airways surplus $90aust
http://homepages.ihug.com.au/~gavmess/shot1.jpg
a small size - taken in the middle of the day with curtains drawn - tv is a 60cm diag to give u some perspective...colour is pretty good (photos don't do justice on all of them
) http://homepages.ihug.com.au/~gavmess/shot2.jpg
the projector in all its glory hehehe
http://homepages.ihug.com.au/~gavmess/shot3.jpg
a shot pulled back to a larger distance...colours were starting to fade abit - you can tell by the colour comparison on the tv
btw these 2 pic shots are tv, also played a bit of colin mcrae which was fun.. i suppose the colour fade is due to the small wattage bulb and the ambient light in the roomhttp://homepages.ihug.com.au/~gavmess/shot4.jpg
the all action "startrek troopers" hehe it was ALOT better than the photos (the resolution, not the actual movie - that still sux
)so, in conclusion, for a night time viewer, with better lenses the 250w 24v globe is ok - but a light with more oomph will be needed methinks
umm
Where to start, well no Im not near done yet I got the basic enclosure but I havent even got the projection lens mounted yet.
As for heat have any of you seen a light fixture that these bulbs go in? they are very small hince it needs a compact bulb and they are AIR tight and get extremely hot but it does not effect the bulbs performance, the reason I have a fan is to keep my box from catching on fire. As for the light comeing out the top I didnt have the top screwed down because I didnt have the fan installed yet so I could leave the top on for very long. I am using the QA-1650
Where to start, well no Im not near done yet I got the basic enclosure but I havent even got the projection lens mounted yet.
As for heat have any of you seen a light fixture that these bulbs go in? they are very small hince it needs a compact bulb and they are AIR tight and get extremely hot but it does not effect the bulbs performance, the reason I have a fan is to keep my box from catching on fire. As for the light comeing out the top I didnt have the top screwed down because I didnt have the fan installed yet so I could leave the top on for very long. I am using the QA-1650
I think this is what im gonna do..
An externally hosted image should be here but it was not working when we last tested it.
The next stage - Improved Contrast...
Hi Guys,
I have been lurking for a while (it has taken me over a month to read all the posts...)
You guys are awesome!
Anyway - down to business: Improved Contrast.
(This has been touched on before, but seems to have been ignored...)
The problem is this - the majority of TFT LCD panels use a special MLA (Micro Lens Array) to allow most of the light from behind to get through. (Generally, 90% of the area of each pixel is taken up by the Thin Film Transistors (TFT) - allowing only 10% for the LCD shutter. The MLA accts as a light condenser for each pixel, and funnels more of the available light through the small apeture.)
The problem here is that the combination of a small hole fed by a small lens causes dispersion of the light coming through the other side. In LCD monitors, this is a good thing because it helps give a wide viewing angle, but for projection, it causes the output beam to be diffused - reducing the contrast (and in many cases brightness) of the final image.
If anybody holds one of these panels up to a light source, you will see that what light does get through is a little blurry and diffused (some panels are affected worse than others in this respect).
This identifies an important point - touched on before in this forum, but never deeply explored - in a normal OHP/Slide projector, the transparency/slide acts as a filter in the optical path. When TFT panels are used, then they become the ACTUAL IMAGE - with each pixel acting as a point source emitter of light.
Luckily, the OHP optial system acting as the basis of most projects here causes the majority of the light being forced through the panel to emerge in the rough direction of the objective lens. However, much of it doesn't, and ends up on the ceiling. This is a good compromise if you are working with an existing OHP configuration, but if you are willing to "play," then it can be optimised...
Classically, if the main objective lens is smaller than the image, the way to increase contrast is to put a larger, longer focal length, PCX collector lens after the image to send all the light rays into the smaller objective lens which has a much shorter focal length, and is preferably achromatic.
Practically, if a small enough LCD panel is being used, this collector could be one of the 5" PCX lenses from SurplusShed.
For an OHP or large LCD panel with an existing objective lens, the only way is to buy the best fresnel panel with the longest focal length and highest "Lines Per Inch" (LPI) density as possible - followed by a large PCV to stop the image being "zoomed" too much by the fresnel.
Before you all start foaming at the mouth (too much), I must explain that the fresnel is not here acting as the actual projection lens - it is playing a small part in the optical path, and if placed correctly, has a minimal impact on actual image quality while DRAMATICALLY increasing both contrast and brightness.
The "correctly" I mention is:
1) Grooves towards the LCD.
2) Close enough to the LCD to reduce optical distortion (less than 2")
3) Far enough away from the LCD to ensure that the main projection objective lens is focussing THROUGH the fresnel and not on it.
The last point is important, and is dependent on (2) as well:
Basically, if the fresnel is too close to the LCD, the grooves interact with the pixels to give moire effects. If the fresnel is too far from the LCD, the moire effect is gone due to light from multiple pixels passing through each point on the fresnel, but then the crappyness of most fresnels (I'm thinking page magnifiers here) distorts the image. Thus if the fresnel is placed close enough to the panel to avoid distortion, but far enough away to reduce the moire effect, it can be used to bend most of the light from the LCD Panel to go the projection objective.
If the fresnel is far enough from the LCD panel at this point, the projection lens will not "see" its grooves, because the objective lens will be focussing through them and directly on the LCD instead (the distance from the objective to the LCD will be effectively increased by the optical effects of the fresnel.)
Overall, for a minimal decrease in image quality, there will be a significant increase in contrast and brightness.
Ok, this thesis is done!
Bill.
Hi Guys,
I have been lurking for a while (it has taken me over a month to read all the posts...)
You guys are awesome!
Anyway - down to business: Improved Contrast.
(This has been touched on before, but seems to have been ignored...)
The problem is this - the majority of TFT LCD panels use a special MLA (Micro Lens Array) to allow most of the light from behind to get through. (Generally, 90% of the area of each pixel is taken up by the Thin Film Transistors (TFT) - allowing only 10% for the LCD shutter. The MLA accts as a light condenser for each pixel, and funnels more of the available light through the small apeture.)
The problem here is that the combination of a small hole fed by a small lens causes dispersion of the light coming through the other side. In LCD monitors, this is a good thing because it helps give a wide viewing angle, but for projection, it causes the output beam to be diffused - reducing the contrast (and in many cases brightness) of the final image.
If anybody holds one of these panels up to a light source, you will see that what light does get through is a little blurry and diffused (some panels are affected worse than others in this respect).
This identifies an important point - touched on before in this forum, but never deeply explored - in a normal OHP/Slide projector, the transparency/slide acts as a filter in the optical path. When TFT panels are used, then they become the ACTUAL IMAGE - with each pixel acting as a point source emitter of light.
Luckily, the OHP optial system acting as the basis of most projects here causes the majority of the light being forced through the panel to emerge in the rough direction of the objective lens. However, much of it doesn't, and ends up on the ceiling. This is a good compromise if you are working with an existing OHP configuration, but if you are willing to "play," then it can be optimised...
Classically, if the main objective lens is smaller than the image, the way to increase contrast is to put a larger, longer focal length, PCX collector lens after the image to send all the light rays into the smaller objective lens which has a much shorter focal length, and is preferably achromatic.
Practically, if a small enough LCD panel is being used, this collector could be one of the 5" PCX lenses from SurplusShed.
For an OHP or large LCD panel with an existing objective lens, the only way is to buy the best fresnel panel with the longest focal length and highest "Lines Per Inch" (LPI) density as possible - followed by a large PCV to stop the image being "zoomed" too much by the fresnel.
Before you all start foaming at the mouth (too much), I must explain that the fresnel is not here acting as the actual projection lens - it is playing a small part in the optical path, and if placed correctly, has a minimal impact on actual image quality while DRAMATICALLY increasing both contrast and brightness.
The "correctly" I mention is:
1) Grooves towards the LCD.
2) Close enough to the LCD to reduce optical distortion (less than 2")
3) Far enough away from the LCD to ensure that the main projection objective lens is focussing THROUGH the fresnel and not on it.
The last point is important, and is dependent on (2) as well:
Basically, if the fresnel is too close to the LCD, the grooves interact with the pixels to give moire effects. If the fresnel is too far from the LCD, the moire effect is gone due to light from multiple pixels passing through each point on the fresnel, but then the crappyness of most fresnels (I'm thinking page magnifiers here) distorts the image. Thus if the fresnel is placed close enough to the panel to avoid distortion, but far enough away to reduce the moire effect, it can be used to bend most of the light from the LCD Panel to go the projection objective.
If the fresnel is far enough from the LCD panel at this point, the projection lens will not "see" its grooves, because the objective lens will be focussing through them and directly on the LCD instead (the distance from the objective to the LCD will be effectively increased by the optical effects of the fresnel.)
Overall, for a minimal decrease in image quality, there will be a significant increase in contrast and brightness.
Ok, this thesis is done!
Bill.
Re: The next stage - Improved Contrast...
I completely agree with the above information, I have been testing some of this myself, and have found that not only popping a large freznel in front on the panel "linearizes" the image path and enhances contrast, but it permits you the use the freznel, if mounted transaxialy on a pivot as a mechanical keystone adjustment. Good post Woneil...
I completely agree with the above information, I have been testing some of this myself, and have found that not only popping a large freznel in front on the panel "linearizes" the image path and enhances contrast, but it permits you the use the freznel, if mounted transaxialy on a pivot as a mechanical keystone adjustment. Good post Woneil...
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.
An externally hosted image should be here but it was not working when we last tested it.
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.
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
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
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
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
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/product_database/hid/displayhid.php?id=71
http://www.lighting.philips.com/nam/product_database/hid/displayhid.php?id=71
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