reflectors
Well i realy wasnt going to advertise as i only have a very limited supply but here is a pic of the ones im selling , the reason mikes looks different is because i sold him a couple without the reflector holder and he made his own, in this pic the reflectors i have are in the holder and are of the ohp type, also the one that mike shows is the ohp type.
Trev
P.S in the pic the reflectors are abit dirty and it was before i got them profesionally polished
Well i realy wasnt going to advertise as i only have a very limited supply but here is a pic of the ones im selling , the reason mikes looks different is because i sold him a couple without the reflector holder and he made his own, in this pic the reflectors i have are in the holder and are of the ohp type, also the one that mike shows is the ohp type.
Trev
P.S in the pic the reflectors are abit dirty and it was before i got them profesionally polished
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reflectors
ok here is a side view, the mount i have for them is high grade aluminium and the reflector cant fall out being clamped by a top riveted plate, this reflector can be mounted upside down if need be or vertical.
Trev
P.S ill try to find a pic of the presision reflector and post it next, ill also metion these reflectors are made out of pyrex.
ok here is a side view, the mount i have for them is high grade aluminium and the reflector cant fall out being clamped by a top riveted plate, this reflector can be mounted upside down if need be or vertical.
Trev
P.S ill try to find a pic of the presision reflector and post it next, ill also metion these reflectors are made out of pyrex.
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Looks much better than my soap laddle. However, IKEA's soup laddle looks quite nice (got to order it soon to try). BTW, how do you should polish a stainless steel soup laddle?
This is the IKEA soup laddle.
It's got 80 mm dia, btw, looks quite round (spherical) to me.
This is the IKEA soup laddle.
It's got 80 mm dia, btw, looks quite round (spherical) to me.
An externally hosted image should be here but it was not working when we last tested it.
That Ikea ladle looks pretty good. If it's round, it's worth a try.
But from what I see people are are confused when it comes to spherical reflectors.
With spherical reflectors, the arc of the bulb has to sit at focal surface in order for the rays to be collimated (straight). Meaning the arc has to sit INSIDE the reflector... not on top of it. So if your using a bulb that has an outter tube with those reflectors... your NOT reflecting the light straight (no matter how much light it actually reflects). Your reflecting the light right back to the source (the arc tube).
http://www.awi-industries.com/relectors.html should clear a few things up for some.
So in order to use those reflectors with bulbs that have an outter tube, your going to have to drill out the sides (like Alan is trying to do). So the bulb sits inside of it. He's got the right idea... even though I dont like his design 🙂
But from what I see people are are confused when it comes to spherical reflectors.
With spherical reflectors, the arc of the bulb has to sit at focal surface in order for the rays to be collimated (straight). Meaning the arc has to sit INSIDE the reflector... not on top of it. So if your using a bulb that has an outter tube with those reflectors... your NOT reflecting the light straight (no matter how much light it actually reflects). Your reflecting the light right back to the source (the arc tube).
http://www.awi-industries.com/relectors.html should clear a few things up for some.
So in order to use those reflectors with bulbs that have an outter tube, your going to have to drill out the sides (like Alan is trying to do). So the bulb sits inside of it. He's got the right idea... even though I dont like his design 🙂
reflecting the light right back to the source is exactly what you need, because you need a point light source. What alan did was to put the arc at the center. because of the size of that laddle, he had to cut the side.
An externally hosted image should be here but it was not working when we last tested it.
18wheeler/ guys
heya 18wheeler i modded your drawing abit i hope u dont mind, this is a typical ohp setup and how they work, its prety self exsplantory but remeber people how lenses work, the light in a lens is always strait in the glass, it bends when it leaves the glass and in this case to a right angle of the surface as u can clearly see with the condenser, also that is the right shape for a reflector, anything more than 1/3 of a parbolic shape will give u too much over throw of light, it will either council itself out or reflect the light in other ares other than the condenser, ie in your enclosure, when i started to fool with reflectors i thought wow how much of a difference it makes, but when i got some pro ones i was like **** me drunk! lol some people think that the small shallow ones waste alot of light, well to be honest i used to think the same, but in practise i have found the shallow small reflectors actually get more light then the home made ones, ie the soup ladel, these small ones are highly engineered so that the rays are going perfectly strait through the condenser not only that but some how to get all of the light from the bulb, in my findings that amount of light wasted in a shallow reflector is about 5-15% depending on bulb and aplication of course and a soup laddel typically 25% why? cos the soup laddel has alot of over throw in the shape, the rays arent strait, its not a micro mirrored surface and the fact most of that light wastage is in diffusion of the light rather than it being reflected, to the people who havnt tried anything but a soup ladel they wont think there is much difference but when u compare a soup laddel to a highly engineered reflector u clearly see the difference as in the picture has atlot more colour, the coulour is a more real life true colour, there is no glare and the image is sharp as can be, its like the picture realy came to life, this isnt an exageration but its the truth, one thing i will experiment on in the very near future is to see weather u see more screen door with a pro reflector than a home made one as the home made one is more difused and not as sharp, just one last thing is that when i changed reflector to the pro ones i noticed one thing that realy stood out, and that is i could project much further as in throw distance with less light loss, this is because of straiter more intense rays of light rather than a bunch of rays semi diffused, another thing i noticed was the lcd and frensel running a whole lot cooler, this is because the rays are more perpedicular going through the lcd pixels and there is less obstruction in each pixel on the lcd to cause the lcd to absorb the light and the light is more polarity corect, anyway hope it helped and lets keep this topic going.
Trev
heya 18wheeler i modded your drawing abit i hope u dont mind, this is a typical ohp setup and how they work, its prety self exsplantory but remeber people how lenses work, the light in a lens is always strait in the glass, it bends when it leaves the glass and in this case to a right angle of the surface as u can clearly see with the condenser, also that is the right shape for a reflector, anything more than 1/3 of a parbolic shape will give u too much over throw of light, it will either council itself out or reflect the light in other ares other than the condenser, ie in your enclosure, when i started to fool with reflectors i thought wow how much of a difference it makes, but when i got some pro ones i was like **** me drunk! lol some people think that the small shallow ones waste alot of light, well to be honest i used to think the same, but in practise i have found the shallow small reflectors actually get more light then the home made ones, ie the soup ladel, these small ones are highly engineered so that the rays are going perfectly strait through the condenser not only that but some how to get all of the light from the bulb, in my findings that amount of light wasted in a shallow reflector is about 5-15% depending on bulb and aplication of course and a soup laddel typically 25% why? cos the soup laddel has alot of over throw in the shape, the rays arent strait, its not a micro mirrored surface and the fact most of that light wastage is in diffusion of the light rather than it being reflected, to the people who havnt tried anything but a soup ladel they wont think there is much difference but when u compare a soup laddel to a highly engineered reflector u clearly see the difference as in the picture has atlot more colour, the coulour is a more real life true colour, there is no glare and the image is sharp as can be, its like the picture realy came to life, this isnt an exageration but its the truth, one thing i will experiment on in the very near future is to see weather u see more screen door with a pro reflector than a home made one as the home made one is more difused and not as sharp, just one last thing is that when i changed reflector to the pro ones i noticed one thing that realy stood out, and that is i could project much further as in throw distance with less light loss, this is because of straiter more intense rays of light rather than a bunch of rays semi diffused, another thing i noticed was the lcd and frensel running a whole lot cooler, this is because the rays are more perpedicular going through the lcd pixels and there is less obstruction in each pixel on the lcd to cause the lcd to absorb the light and the light is more polarity corect, anyway hope it helped and lets keep this topic going.
Trev
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Just remember guys to follow the light from the bulb, not the reflector to the bulb and u will see how it works, and just a word of warning on reflectors, they normally have a 1:1 focal so the bigger the reflector the bigger the focal length is, hence big is not always better
Trev
Trev
AH.... I think you all need to study up a bit!
Number 1 - Condensers dont spread light! They condense it into a beam. Many people on the board have it backwards! More light condensed into a beam lets the fresnel collect and spread more light over it's surface.
Number 2 - 18 wheeler took that from the AWI site. When the light is reflected back to the source that means it's reflected back to the arc tube and NOT straight. The arc tube needs to sit INSIDE the reflector for the light to be reflected straight. So ace3000_1's drawing is incorrect!
Ace, your setup is great... but it's not working the way you think it is.
18 Wheeler- your right... you do need a point source of light. But the problem with the light being reflected back to the arc is the bulb runs alot hotter and doesnt last as long as it could.
Number 1 - Condensers dont spread light! They condense it into a beam. Many people on the board have it backwards! More light condensed into a beam lets the fresnel collect and spread more light over it's surface.
Number 2 - 18 wheeler took that from the AWI site. When the light is reflected back to the source that means it's reflected back to the arc tube and NOT straight. The arc tube needs to sit INSIDE the reflector for the light to be reflected straight. So ace3000_1's drawing is incorrect!
Ace, your setup is great... but it's not working the way you think it is.
An externally hosted image should be here but it was not working when we last tested it.
18 Wheeler- your right... you do need a point source of light. But the problem with the light being reflected back to the arc is the bulb runs alot hotter and doesnt last as long as it could.
jcb
lol u need to study abit i think, i got told by an optical engineer how this stuff works, this guy has a major degree in how lenses and reflectors work lol dont tell me i need to study, look at yourself, condensers condense light into a beam when u use a pair of them, not 1, 1 pcx condenser wich is a magnifyer or condenser, is a magnifier used as 1 over a light and thefore bends the rays outwards to a wide beam, 2 condensers control the light into a fine strait beam as one is a transmiter and working as a colector while the other receives and concentraits the beam into the desired beam width. U want to know the beam width? the beam width is the diameter of the condenser pair and it only works with 2 of the same diameter lenses, they are also facing front to front to each other and are nearly touching.
have a look at the drawing below
Trev
lol u need to study abit i think, i got told by an optical engineer how this stuff works, this guy has a major degree in how lenses and reflectors work lol dont tell me i need to study, look at yourself, condensers condense light into a beam when u use a pair of them, not 1, 1 pcx condenser wich is a magnifyer or condenser, is a magnifier used as 1 over a light and thefore bends the rays outwards to a wide beam, 2 condensers control the light into a fine strait beam as one is a transmiter and working as a colector while the other receives and concentraits the beam into the desired beam width. U want to know the beam width? the beam width is the diameter of the condenser pair and it only works with 2 of the same diameter lenses, they are also facing front to front to each other and are nearly touching.
have a look at the drawing below
Trev
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🙂 look, all I'm saying... is that your drawing (the one on the previous page)... is wrong. And a single condenser doesnt work the way you have it show in your diagram.
The picture above is correct and that wasnt what I was talking about. You misunderstood me. The drawing above is focusing to a point... not a beam.
The picture above is correct and that wasnt what I was talking about. You misunderstood me. The drawing above is focusing to a point... not a beam.
jcb
jcb so your trying to tell me a frensel can majically make a 1" beam of light over the whole area? wouldnt that be called a hot spot?
jcb so your trying to tell me a frensel can majically make a 1" beam of light over the whole area? wouldnt that be called a hot spot?
jcb
your crazy man lol i can tell u havnt fooled with this stuff or if u have in a so different way thinking and knowing are too different things!
your crazy man lol i can tell u havnt fooled with this stuff or if u have in a so different way thinking and knowing are too different things!
majically?
No it's not magic. Producing a collimated beam of light from a point source is the perfect application for a fresnel lens and what they are designed for. The condenser takes care of the hotspot and helps focus more light towards the fresnel.
Thats what a double fresnel on an OHP setup does. It takes light from a point source and turns it into a collimated beam... then the top fresnel takes the collimated light and focuses it to the objective lens.
No it's not magic. Producing a collimated beam of light from a point source is the perfect application for a fresnel lens and what they are designed for. The condenser takes care of the hotspot and helps focus more light towards the fresnel.
Thats what a double fresnel on an OHP setup does. It takes light from a point source and turns it into a collimated beam... then the top fresnel takes the collimated light and focuses it to the objective lens.
ok ok im sorry to but in here but this is a write up on what a condenser actulay does and yes ace you are correct the condenser does spread the light to cover the complete surface of the fresnel
yes i do study up quite a bit!!
Condenser
The condenser is the most important lens in the illumination system.The condenser concentrates light from the filament image into partially coherent light onto the specimen plane.This light is formed into a cone shape that spreads out from the specimen tword the objective lens.The condenser must be able to form a light cone with a sufficiently large angle to fill the entire back focal plane of the objective lens.
yes i do study up quite a bit!!
Condenser
The condenser is the most important lens in the illumination system.The condenser concentrates light from the filament image into partially coherent light onto the specimen plane.This light is formed into a cone shape that spreads out from the specimen tword the objective lens.The condenser must be able to form a light cone with a sufficiently large angle to fill the entire back focal plane of the objective lens.
jcb
"Lenses bend light"
This one is a bit of a subtle distinction. Light will bend when going from one medium to another if the two materials have a different index of refraction. The difference between the index of refraction of the two materials will also delineate how much the light will get bent. So, light going from air to glass gets bent a lot. If you took that lens under water if would bend light less. Out in space, it would bend light more.
And, all of the bending happens at the surface where the two materials meet each other. The light bends when it leaves the air and enters the glass, not inside of the glass, and bends again when it leaves the glass and enters the air.
How much the light gets bent is also determined by the angle that the ray of light crosses from one material into another. If light hits the glass perpendicular to the surface where it enters, it will not get bent at all.
That also explains how a Fresnel lens works-- it's nearly all surface and no middle, but on a lens, the surfaces do all of the work. (By the way, if you start designing a projection system that uses lasers, stay away from fresnels; they won't work well with monochromatic light.)
And a flat pane of glass is really only a special type of lens. It does bend the light entering it, but the light gets bent the other direction when it goes out the other side. The ray of light does get shifted over a little bit, but will always come out of the other side in parallel with the ray that went in. With really thick glass, it gets shifted over a bunch. Try looking though the thick bullet-proof stuff at the bank and you'll see what I mean.
"Lenses bend light"
This one is a bit of a subtle distinction. Light will bend when going from one medium to another if the two materials have a different index of refraction. The difference between the index of refraction of the two materials will also delineate how much the light will get bent. So, light going from air to glass gets bent a lot. If you took that lens under water if would bend light less. Out in space, it would bend light more.
And, all of the bending happens at the surface where the two materials meet each other. The light bends when it leaves the air and enters the glass, not inside of the glass, and bends again when it leaves the glass and enters the air.
How much the light gets bent is also determined by the angle that the ray of light crosses from one material into another. If light hits the glass perpendicular to the surface where it enters, it will not get bent at all.
That also explains how a Fresnel lens works-- it's nearly all surface and no middle, but on a lens, the surfaces do all of the work. (By the way, if you start designing a projection system that uses lasers, stay away from fresnels; they won't work well with monochromatic light.)
And a flat pane of glass is really only a special type of lens. It does bend the light entering it, but the light gets bent the other direction when it goes out the other side. The ray of light does get shifted over a little bit, but will always come out of the other side in parallel with the ray that went in. With really thick glass, it gets shifted over a bunch. Try looking though the thick bullet-proof stuff at the bank and you'll see what I mean.
jcb
take the top off your ohp and look at the roof, if that beam was strait it would be a colum of light, thats asuming u have a condenser
take the top off your ohp and look at the roof, if that beam was strait it would be a colum of light, thats asuming u have a condenser
so if I were to incorporate a condenser in my projector, would I want to put it at the focal point of the fresnel? Would I want to make it closest to my light source as possible to collect the light? I also have 77mm diameter heat absorbing glass, polarizer, and UV filter, how would I want to position these in my projector?
The guy at the camera shop across the street has a bunch of different condensers, what should I tell him I want? I'm using the DIY labs 12.2" fresnel and a 250W HQI bulb. He also said he has a bunch of old projector lenses laying around in the back. He showed me some condenser lenses and they looked a little small, (about 2"diameter) but I'm sure he has bigger ones. Any advice is welcome!
The guy at the camera shop across the street has a bunch of different condensers, what should I tell him I want? I'm using the DIY labs 12.2" fresnel and a 250W HQI bulb. He also said he has a bunch of old projector lenses laying around in the back. He showed me some condenser lenses and they looked a little small, (about 2"diameter) but I'm sure he has bigger ones. Any advice is welcome!
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