Yes, I mean 200 lumens with 400w bulb. Of course this is only speculation at this point. Testing still needs to be done. People see a bought projector that has 2000 lumens output and compare it a diy projector and guess that the diy projector puts out 1300 lumens. The problem with that is the store bought one was never anywhere near 2000 lumens in the first place. Real world testing will prove or disprove these claims that are being made.
yes you are doing a good work with the luxmeter.
have a look here, is a user from lumenlab with a luxmeter (post 18 and on)
http://www.lumenlab.com/forums/index.php?showtopic=6081
he has somewhere 160 ansi lumens (400W lamp).
I am collecting information as well, guy grotke's meassuremnt as you know, let´s see what's the real average value for diyprojectors.
let's leave 1300 lumens for dreamers. 😀
have a look here, is a user from lumenlab with a luxmeter (post 18 and on)
http://www.lumenlab.com/forums/index.php?showtopic=6081
he has somewhere 160 ansi lumens (400W lamp).
I am collecting information as well, guy grotke's meassuremnt as you know, let´s see what's the real average value for diyprojectors.
let's leave 1300 lumens for dreamers. 😀
Rox said:
I wouldn't call them dreamers. It's more like a lack of understanding or believing misinformation that gets passed around. An example is someone uses a hubcap for a reflector and says "I got an 80% increase in light output!" The response is "Wow. Awesome results. Where can I get one!" My response is "Wow. Awesome results. prove it." If we test different equipment combinations and can show real data that proves increased light output then everyone benefits. We can show what works and what doesn't. My attitude towards diy projectors is let's make it the best we can with the resourses we have.
Mike
Yes, i agree with your philosofy. But i don´t like being cheated, who does?
I also found a way to do first surface mirror from an ordinary mirror and a "decapante" in spanish, sorry i don´t know how is it in english, it is used to restore the paint from a surface, you aplly and let it work, then after 20min you can clean the surface. I don´t know if you have heard about, i found it on spanish forum, don´t know if here is as well. What i mean is, i tried it myself and did a frist surface mirror that way. well the result was great, but then after some weeks, the mirror starts to oxidate and so the image cuality falls down quicly.
that's because the crome was unprotected after the "decapante" erased the back protective layer.
What i mean with this words is that the things must be tested/proved/confirmed... and that´s the comunity for 😀. In your case, you bought a luxmeter, that i apreciate and think it helps very much to the comunity 😀.
Then, i found as well, that when i try to discuss some aspects with some people, they do not colaborate and take all things against them, well, maybe they aren´t good guys 😀.
I also found a way to do first surface mirror from an ordinary mirror and a "decapante" in spanish, sorry i don´t know how is it in english, it is used to restore the paint from a surface, you aplly and let it work, then after 20min you can clean the surface. I don´t know if you have heard about, i found it on spanish forum, don´t know if here is as well. What i mean is, i tried it myself and did a frist surface mirror that way. well the result was great, but then after some weeks, the mirror starts to oxidate and so the image cuality falls down quicly.
that's because the crome was unprotected after the "decapante" erased the back protective layer.
What i mean with this words is that the things must be tested/proved/confirmed... and that´s the comunity for 😀. In your case, you bought a luxmeter, that i apreciate and think it helps very much to the comunity 😀.
Then, i found as well, that when i try to discuss some aspects with some people, they do not colaborate and take all things against them, well, maybe they aren´t good guys 😀.
Here here Guy!
Although there is a standard for measuring lumens output there is no regulation of what can be advertised.
It is next to worthless to take most manufacturers stated lumens as truth. I really don't see much point in measuring DIY PJ's lumens for any other reason than a stadard to compare our results and the results of new experimental bulbs and optics setups (if meters were cheaper and easier to come by). Comparing to lumen outputs of commercial PJ's is close to worthless. The only real comparison that could be made is like Guy said, all on at the same time viewed at a distance.
Although there is a standard for measuring lumens output there is no regulation of what can be advertised.
It is next to worthless to take most manufacturers stated lumens as truth. I really don't see much point in measuring DIY PJ's lumens for any other reason than a stadard to compare our results and the results of new experimental bulbs and optics setups (if meters were cheaper and easier to come by). Comparing to lumen outputs of commercial PJ's is close to worthless. The only real comparison that could be made is like Guy said, all on at the same time viewed at a distance.
well, if we can meassure the ansi from a comertial (preferably new bulb) we can have an idea as well. (is that what mikey p and guy grotke are doing? please share your investemets 😀)
joew26mpls said:
I totally agree. Taking stated lumens as truth is an example of the misinformation that people do believe. Testing available optical setups for the diy community is all I'm interested in. But I do imagine that in some point in the future I will measure some "2200 lumen light cannon" to see what it actually does produce for light output, just out of curiousity.
let's be objective
I see that 22% number being quoted quite a bit. I think I should state again: The 22% increase in lux I see with a spherical reflector is only valid for MY projector with MY reflector!
I am using a unique reflector. (Silver-plated quiche mold) So other reflectors will probably have different performance. My original source for the stainless steel mold I started with no longer lists them on their website, so I doubt that anybody can duplicate my reflector precisely.
I see that 22% number being quoted quite a bit. I think I should state again: The 22% increase in lux I see with a spherical reflector is only valid for MY projector with MY reflector!
I am using a unique reflector. (Silver-plated quiche mold) So other reflectors will probably have different performance. My original source for the stainless steel mold I started with no longer lists them on their website, so I doubt that anybody can duplicate my reflector precisely.
Check this attached guy;
if we place the pre-cond lens where intersets the focalpoint-lcd triangle with the lens diameter exactly, and then ensure the virtual arc is at rear fresnell focal point, then there is an issue;
the full arc lengh is not being seen from every point of the lcd (the corner does see only half arc lengh and the green pixel is the critical point where full arc lenght is seen, so it could be the cause of dim edges.
if we place the pre-cond lens where intersets the focalpoint-lcd triangle with the lens diameter exactly, and then ensure the virtual arc is at rear fresnell focal point, then there is an issue;
the full arc lengh is not being seen from every point of the lcd (the corner does see only half arc lengh and the green pixel is the critical point where full arc lenght is seen, so it could be the cause of dim edges.
Attachments
wrong place for arc
If you use a pre-condensor lens, then you can't put the arc at the focal length of the fresnel and still get parallel rays from the fresnel. You have to move the arc closer to the lens.
But aside from that, I agree with your premise: If the light from only part of the arc gets to the corners of the fresnel, then they will be much dimmer.
I think the best procedure is to place the pre-condensor lens at the right distance from the fresnel, so it would intersect the cone of light coming from a point-source at the focal length from the fresnel. Start with the lamp arc at that point, but then move it towards the pre-condensor lens until the cone of light expands to light the fresnel evenly.
In my projector, the corners are not dim because of a pre-condensor lens problem: I don't use a pre-condensor lens. With a 220 mm fl condensor fresnel and a 15" LCD, a pre-condensor lens does not give you much more light output.
If you use a pre-condensor lens, then you can't put the arc at the focal length of the fresnel and still get parallel rays from the fresnel. You have to move the arc closer to the lens.
But aside from that, I agree with your premise: If the light from only part of the arc gets to the corners of the fresnel, then they will be much dimmer.
I think the best procedure is to place the pre-condensor lens at the right distance from the fresnel, so it would intersect the cone of light coming from a point-source at the focal length from the fresnel. Start with the lamp arc at that point, but then move it towards the pre-condensor lens until the cone of light expands to light the fresnel evenly.
In my projector, the corners are not dim because of a pre-condensor lens problem: I don't use a pre-condensor lens. With a 220 mm fl condensor fresnel and a 15" LCD, a pre-condensor lens does not give you much more light output.
Re: wrong place for arc
the picture i post is not the real arc at the rear fresnell's focalpoint. It is the virtual arc (real arc is somewhere between virtual arc ant the pre-cond lens, it depends on the focal lengh of the pre-cond lens, but now forget the real arc, think about the virtual arc at rear fresnells focal point)
The intersection of the lcd size and rear fresnells focal point triangle with the diameter of the pre-cond lens to determine the lens placement will never work if we place the virtual arc at rear fresnells focal point.
I sugest a larger diameter precondenser lens so full virtual arc will be seen from every point of the lcd. (the diameter of the precondenser lens is like a window if we consider the virtual arc, mean there wont be refraction for the ligh of the virtual arc)
Guy Grotke said:
the picture i post is not the real arc at the rear fresnell's focalpoint. It is the virtual arc (real arc is somewhere between virtual arc ant the pre-cond lens, it depends on the focal lengh of the pre-cond lens, but now forget the real arc, think about the virtual arc at rear fresnells focal point)
The intersection of the lcd size and rear fresnells focal point triangle with the diameter of the pre-cond lens to determine the lens placement will never work if we place the virtual arc at rear fresnells focal point.
I sugest a larger diameter precondenser lens so full virtual arc will be seen from every point of the lcd. (the diameter of the precondenser lens is like a window if we consider the virtual arc, mean there wont be refraction for the ligh of the virtual arc)
If i want a unsplit fresnel design, i still need a 330mm & 220mm fresnels right? Also, could i put the projector on a shorter table, angled up to the screen, but have the screen angled down a bit to correct the angle?
Sorry about the two ack to back posts, but i forgot to ask this and i really need to know. Iordered the fresnels set from www.diyprojectorcompany.com, but since i live in Canada i cant use paypal because i dont have a confirmed address. But Lumenlab will let me use paypal for their lens's. Are the fresnels the same at both these sites, because lumenlab doesnt really have much description.
unsplit design
As long as the center of the projector beam is perpendicular to the screen, then you won't need any keystone correction. You can put the projector on the floor pointing straight up at the ceiling, if you want to.
Actually, there is another reason to point the projector up at a tilted screen as you propose: If you use a high-gain curved screen, then the best image is viewed from a position very close to the projector.
If the tilted screen is to difficult to get right, you can always put your projector up on a shelf or table, to get the projection lens up to the level of the screen center. Then you can use a normal vertical screen.
As long as the center of the projector beam is perpendicular to the screen, then you won't need any keystone correction. You can put the projector on the floor pointing straight up at the ceiling, if you want to.
Actually, there is another reason to point the projector up at a tilted screen as you propose: If you use a high-gain curved screen, then the best image is viewed from a position very close to the projector.
If the tilted screen is to difficult to get right, you can always put your projector up on a shelf or table, to get the projection lens up to the level of the screen center. Then you can use a normal vertical screen.
Obviously this is the easiest way to do it, but than i dont want the PJ to be in the way of the screen. When you do the tilted screen option, how exact do you have to be? what if it is off a few degrees, will you notice at all in the quality or brightness or something else?
tilted screen
If it is off far enough, then you will notice the keystone distortion. It is all a matter of individual perception. A little bit is not disturbing when you are watching a video. I remember a whole year of trigonometry class, looking at an OHP screen with horrible keystone. No problem reading the teacher's equations. 😀
And Rox, regarding post 51: I thought your picture might confuse some other people, which is why I mentioned the real arc placement. But I was also agreeing with your statement: "If the light from only part of the arc gets to the corners of the fresnel, then they will be much dimmer."
I think the cone of light from a pre-condensor lens will have a lux level that falls very rapidly toward the edge, because of the effect you explained. The best way to avoid using that part of the light cone, is to adjust the lamp arc to pre-condensor lens distance with the projector on. Then you can look at a mostly-white test image, and adjust the distance to get the light levels more uniform over the whole image. Most overhead projectors have a condensor adjustment, just for this purpose.
If it is off far enough, then you will notice the keystone distortion. It is all a matter of individual perception. A little bit is not disturbing when you are watching a video. I remember a whole year of trigonometry class, looking at an OHP screen with horrible keystone. No problem reading the teacher's equations. 😀
And Rox, regarding post 51: I thought your picture might confuse some other people, which is why I mentioned the real arc placement. But I was also agreeing with your statement: "If the light from only part of the arc gets to the corners of the fresnel, then they will be much dimmer."
I think the cone of light from a pre-condensor lens will have a lux level that falls very rapidly toward the edge, because of the effect you explained. The best way to avoid using that part of the light cone, is to adjust the lamp arc to pre-condensor lens distance with the projector on. Then you can look at a mostly-white test image, and adjust the distance to get the light levels more uniform over the whole image. Most overhead projectors have a condensor adjustment, just for this purpose.
Re: tilted screen
this condensor adjustment you mention on OHP, i thought it was the bulb position, so a significative throw change (so projection lens change as well) needs a light cone adjustement, thats why i thought this weel moved the light/condensor group up/down.
What i mean with my picture is that if we make the virtual arc be at rear fresenlls focal point, and also do the precondensor lens diameter intersect with the fresenlls, triangle (the triangle with the focal point and the lcd diagonal) then we allways will have dimer corners, because there is no way to see full arc from all lcd points.
I think making the virtual arc come from the rear fresnells focal point is a good idea (so parallel light will go throw the lcd), but the lens placement is not correct, we need a larger diameter lens than what you sugested or a closer placement for this lens diameter you talk about.
the goal is making a virtual arc at rear fresnells focal and ensuring this arc will be seen from every point of the lcd. Do you agree?
Guy Grotke said:
this condensor adjustment you mention on OHP, i thought it was the bulb position, so a significative throw change (so projection lens change as well) needs a light cone adjustement, thats why i thought this weel moved the light/condensor group up/down.
What i mean with my picture is that if we make the virtual arc be at rear fresenlls focal point, and also do the precondensor lens diameter intersect with the fresenlls, triangle (the triangle with the focal point and the lcd diagonal) then we allways will have dimer corners, because there is no way to see full arc from all lcd points.
I think making the virtual arc come from the rear fresnells focal point is a good idea (so parallel light will go throw the lcd), but the lens placement is not correct, we need a larger diameter lens than what you sugested or a closer placement for this lens diameter you talk about.
the goal is making a virtual arc at rear fresnells focal and ensuring this arc will be seen from every point of the lcd. Do you agree?
"Do you agree?"
Yes, I do agree. We really need to put the virtual lamp arc at the position where it intersects the cone of light that would come from a true point source. That way light from all parts of the arc can get through the pre-condensor lens.
If you miss one end of the arc, you lose quite a lot of the available light. (The brightest parts of a MH arc are at the ends.)
Yes, I do agree. We really need to put the virtual lamp arc at the position where it intersects the cone of light that would come from a true point source. That way light from all parts of the arc can get through the pre-condensor lens.
If you miss one end of the arc, you lose quite a lot of the available light. (The brightest parts of a MH arc are at the ends.)
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