Question
Hi,
I am kind of new here, so I apologize in advance
for this simple question, but I have just got to ask:
If you have a point 'light source', and you put it behind
an LCD panel, would it not just project the LCD image
over the wall? (like hand shadows)
I don't have an LCD panel yet, so I can't test it. But
I think that if a light beam pass the LCD strait, then
it is possible. On the other hand if a light beam that
pass the LCD is scattered in all directions then it isn't
possible.
If it is possible but the light source is not a point, than
many images would be cast on the wall from the many
virtual point light source, and so the image would not be
clear.
You can test it with a Laser beam or with a light beam
or with a point light source if you know how to make one.
Hi,
I am kind of new here, so I apologize in advance
for this simple question, but I have just got to ask:
If you have a point 'light source', and you put it behind
an LCD panel, would it not just project the LCD image
over the wall? (like hand shadows)
I don't have an LCD panel yet, so I can't test it. But
I think that if a light beam pass the LCD strait, then
it is possible. On the other hand if a light beam that
pass the LCD is scattered in all directions then it isn't
possible.
If it is possible but the light source is not a point, than
many images would be cast on the wall from the many
virtual point light source, and so the image would not be
clear.
You can test it with a Laser beam or with a light beam
or with a point light source if you know how to make one.
Size of the reflector must match arcsize
Because nobody else have mentioned this, and I´m sorry I didn´t mentioned this along time ago. There is one important rule with all reflectors:
Big arc size = Big reflector size, small arc size = small reflector size.
There are many example of this, in pro-projectors they use a 50mm reflector and the arc size is 1-2mm, 50mm halogenreflectorlamps 12V have a filament size of 1-2mm, PAR30 with a reflector size of 100mm have a filament size of 10mm. The arc size in a cdm-t lamp is 9mm, so to get the best resultat you need a reflector size of 100mm or bigger.
I have self tested the cdm-t lamp with a 50mm halogenreflector, not good at all.
Because nobody else have mentioned this, and I´m sorry I didn´t mentioned this along time ago. There is one important rule with all reflectors:
Big arc size = Big reflector size, small arc size = small reflector size.
There are many example of this, in pro-projectors they use a 50mm reflector and the arc size is 1-2mm, 50mm halogenreflectorlamps 12V have a filament size of 1-2mm, PAR30 with a reflector size of 100mm have a filament size of 10mm. The arc size in a cdm-t lamp is 9mm, so to get the best resultat you need a reflector size of 100mm or bigger.
I have self tested the cdm-t lamp with a 50mm halogenreflector, not good at all.
Attachments
hi mathias,
what defines the size?
is it the wire in the bulb that defines the size or is the body of the bulb as the wire only brings the halogen to lighten.
so then the body of the 50W bulb you posted is nearly the same size like the light chamber of the cdm-t.
and may be you had to cut away too much from the 50mm reflector...
i have a 56mm reflector... the problem is i want to build a compact pj so i can't afford to use a 110mm reflector or even bigger...
i had very good results with this reflector as the beam was VERY intense...
i also tried a 110mm reflector and the bulb was as big as the 20W bulb in your post
and i had a PAR 20 bulb from Osram (Halopar 20) which had the same bulb in it like the the PAR 30 bulb and a reflektor with only 57mm...
only differences between those 2 was the angle of the light, and i want as less angle as possible the make a paralell beam for the condensor...
so my question is:
is there a specific rule that defines the size of a reflector for every lamp?
i thought:
the smaller the reflector the smaller the light angle the intenser the light...
what were the problems with the 50mm reflector?
i am trying to build a light machine like ace did, and i thought the intensiest light would be best; to be continued...
what defines the size?
is it the wire in the bulb that defines the size or is the body of the bulb as the wire only brings the halogen to lighten.
so then the body of the 50W bulb you posted is nearly the same size like the light chamber of the cdm-t.
and may be you had to cut away too much from the 50mm reflector...
i have a 56mm reflector... the problem is i want to build a compact pj so i can't afford to use a 110mm reflector or even bigger...
i had very good results with this reflector as the beam was VERY intense...
i also tried a 110mm reflector and the bulb was as big as the 20W bulb in your post
and i had a PAR 20 bulb from Osram (Halopar 20) which had the same bulb in it like the the PAR 30 bulb and a reflektor with only 57mm...
only differences between those 2 was the angle of the light, and i want as less angle as possible the make a paralell beam for the condensor...
so my question is:
is there a specific rule that defines the size of a reflector for every lamp?
i thought:
the smaller the reflector the smaller the light angle the intenser the light...
what were the problems with the 50mm reflector?
i am trying to build a light machine like ace did, and i thought the intensiest light would be best; to be continued...
i agree with you mathias that there may be too small reflectors for certain bulbs and that the 50mm is too small, because you have to cut away so much to make the bulb fit, but i think the 56mm reflector is enough
we will finally see when i start my first projected pics with the new light unit i am planning. may be i am proofen wrong then...
we will finally see when i start my first projected pics with the new light unit i am planning. may be i am proofen wrong then...
The filament size in a halogenlamp is the size of the rolled up thin wire in the glassbody, that is the only thing that give light, 1-2mm for 20-50W 12V Halogen and 10mm for 75W 230V Halogen.
Of course a big reflector with a small arc is not wrong, thats why you can find 110mm reflector with bulb big as the 20W bulb in my picture.
You can only get 10 degrees PAR20 lamp with 50W and I think that that filament is smaller than the PAR30 filament. 30 degrees PAR20 version goes up to 100W, with a bigger filament size.
Yes this is true, smaller area more light, but with a big arc size you will not get parallel light beam out from the smallreflector and this was the problem with my 50mm lamp. I don´t know if there is a mathematical rule for this, but the distans to the reflectingmaterial should be as big as possible with a big arc size, because the angle difference gets smaller. So this rule will be true till somebody find a mathematical rule.
Big arc size = Big reflector size, small arc size = small reflector size(Can also be big).
Ah huh, but its also horizontal, when u put a lamp in a parabolic reflector and if the arc is running long ways u will get unwanted results, this is cos the arc is longer then the focal point, some of the bulbs arc will be in the focal point and some wont, this will result in non true paralelle light being reflected from the reflector.
Trev
Actually thats false, the bigger the reflector the more light it can gather, only when u gather that light to a point it will be brither then having a small reflector reflecting only part of the light. The closer the bulb is to the reflector, the brighter the reflected light will be.
Trev
thx trev.
another question:
i am thinking about using two 150W lamps. But before i go and buy that stuff i thought about a way to make one spot out of two.
the black things are the mirrors; you see what the problem is, either i have two spots or i loose light because not all the light hits mirrors and go into the one spot. i want to have both spots fully made into one for doubling the lumen numbers
I also thought about using prisms i can use but i didn't find a good solution.
What do you think?
here is a quick drawing of what i meant
slize
another question:
i am thinking about using two 150W lamps. But before i go and buy that stuff i thought about a way to make one spot out of two.
the black things are the mirrors; you see what the problem is, either i have two spots or i loose light because not all the light hits mirrors and go into the one spot. i want to have both spots fully made into one for doubling the lumen numbers
I also thought about using prisms i can use but i didn't find a good solution.
What do you think?
here is a quick drawing of what i meant
slize
Attachments
here it is from a commercial projector, but i don't really get how they make it...
do they use it like in my drawing on the left side?
if it is like that, that's not what i want to achieve. i wanna have one spot out of thes two? isn't there something like a beamsplitter? (not the regular one, i know it works different)
i guess their mirrors are not 90°
but where do i have to focus both spots then; on the condensor, or on the fresnel, i don't really know
do they use it like in my drawing on the left side?
if it is like that, that's not what i want to achieve. i wanna have one spot out of thes two? isn't there something like a beamsplitter? (not the regular one, i know it works different)
i guess their mirrors are not 90°
but where do i have to focus both spots then; on the condensor, or on the fresnel, i don't really know
Attachments
Slize
heya buddy, with that idea on the left it will work, a prisim is the best thing for us because the fs mirror needs to be beveled 45deg on both mirrors so the light is 1 continuos wide beam, u will not get it any brighter trying to get it into a narrow beam from the 2 bulbs, but u will get it brigter if the beam is concentrated to only cover half of the lcd per bulb as that beam on its own is more intense and is more concentrated covering a smaller area rather then covering a bigger area. With this ideas u will need only 1 frensel, 1 that goes over the front of the lcd to guide the light through the projection lens, the light that will come from these mirrors will already be paralelle. This system i dont see as being a big advantage in certain ways, but i have tricks up my sleeve for this as ive fooled with this mid last year and found enhancments while testing, cash flow was the thing that stopped me and damage to my eyes.
Trev
heya buddy, with that idea on the left it will work, a prisim is the best thing for us because the fs mirror needs to be beveled 45deg on both mirrors so the light is 1 continuos wide beam, u will not get it any brighter trying to get it into a narrow beam from the 2 bulbs, but u will get it brigter if the beam is concentrated to only cover half of the lcd per bulb as that beam on its own is more intense and is more concentrated covering a smaller area rather then covering a bigger area. With this ideas u will need only 1 frensel, 1 that goes over the front of the lcd to guide the light through the projection lens, the light that will come from these mirrors will already be paralelle. This system i dont see as being a big advantage in certain ways, but i have tricks up my sleeve for this as ive fooled with this mid last year and found enhancments while testing, cash flow was the thing that stopped me and damage to my eyes.
Trev
sorry to hear that,
so you don't think it is worth to go for as you already tested it? cause the problem is, i'd love to use this cdm-t bulb but 12000 lumens is not enough for 15" tft. i already tested it.
I am using a 400 HQI-TS with 36000 lumens but i think it is too hot too heavy too big, the picture is nice though but i am searching a way to use the cdm s, and i thought i could increase light output to let s say 24000 lumens with this way...
I cant even use a reflector with the 400W cause it is so big, so i think i loose light anyways, that's the reason i wanted to go for 300W and an efficent way to use light
slize
p.s.: here is the link i got the lumen numbers from:
http://www.strassenlicht.de/technik/lampen/typen1.htm
so you don't think it is worth to go for as you already tested it? cause the problem is, i'd love to use this cdm-t bulb but 12000 lumens is not enough for 15" tft. i already tested it.
I am using a 400 HQI-TS with 36000 lumens but i think it is too hot too heavy too big, the picture is nice though but i am searching a way to use the cdm s, and i thought i could increase light output to let s say 24000 lumens with this way...
I cant even use a reflector with the 400W cause it is so big, so i think i loose light anyways, that's the reason i wanted to go for 300W and an efficent way to use light
slize
p.s.: here is the link i got the lumen numbers from:
http://www.strassenlicht.de/technik/lampen/typen1.htm
Slize
Yeah its a goer buddy, but bear in mind your going to use 2 bulbs lol, just make sure the light is paralelle, this is very important, ill have another crack it this soon for ya, ive got a billion projects going now so time is abit short, (ive prety much designed my next 3 projectors ready to go).
Trev
Yeah its a goer buddy, but bear in mind your going to use 2 bulbs lol, just make sure the light is paralelle, this is very important, ill have another crack it this soon for ya, ive got a billion projects going now so time is abit short, (ive prety much designed my next 3 projectors ready to go).
Trev
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