Some one say reflector?
I FOUND IT!! I was at the supply house today and I was walking around the warehouse with my salesman friend and I saw this light I almost craped my pants I went and looked at it, it had a 11 in diag. reflector near mirror finish on the inside. I said I want that lucky for me the light was missing a few parts so hes like umm put it in your truck and don't bring it back. WOOT FREE 99!
I FOUND IT!! I was at the supply house today and I was walking around the warehouse with my salesman friend and I saw this light I almost craped my pants I went and looked at it, it had a 11 in diag. reflector near mirror finish on the inside. I said I want that lucky for me the light was missing a few parts so hes like umm put it in your truck and don't bring it back. WOOT FREE 99!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Xterrian:
I just had lunch with a friend of mine in the physics dept. He designs telescopes for a living and he told me the secondary would not be a problem. I still have trouble to believe him, but he gave a few good examples. For example, why don't you see dust on your camera lens when you take a picture? If you look through binoculars and you stick your finger in front, can you see it? (He claims you can't). We may not have a problem with blocked pixels, but I still need to give this more thought.
CR
I just had lunch with a friend of mine in the physics dept. He designs telescopes for a living and he told me the secondary would not be a problem. I still have trouble to believe him, but he gave a few good examples. For example, why don't you see dust on your camera lens when you take a picture? If you look through binoculars and you stick your finger in front, can you see it? (He claims you can't). We may not have a problem with blocked pixels, but I still need to give this more thought.
CR
little idea
this is what im working on. im im not sure you will understand it.
check out page 129 the last post has a web site that shows u guys a littel bid on what im doing, sorry i cant put a real picture cause im missing the cord to my cam.if you got ?'s ill try to anwser them etc. 😀 😀 😀 😀
also i just f*ck up the pic i drawed out for u, it kept say it was to big . i did some stuff to it now its fu*cked but its on here
can some one tell me how to put pic's on a post etc. thank you
this is what im working on. im im not sure you will understand it.
check out page 129 the last post has a web site that shows u guys a littel bid on what im doing, sorry i cant put a real picture cause im missing the cord to my cam.if you got ?'s ill try to anwser them etc. 😀 😀 😀 😀
also i just f*ck up the pic i drawed out for u, it kept say it was to big . i did some stuff to it now its fu*cked but its on here
can some one tell me how to put pic's on a post etc. thank you
Attachments
It's the same, if you take a blind with a little whole at a lens, or make a black point on that lens! The reason: EVERY point of an object is imaged through EVERY point of the lens, so blocking a part of a lens only takes away some brightness, nevertheless the whole image is on the screen. As long as the complete image is seen by a part of the lens or mirror, there is no lack of image! Geometrical optics....!
xblocker
xblocker
biteon!!!
i think that the water in the coffe can wil get dirty ( in the best scenario), it also may leak and set a fire in your house!!!
😀 😀 😀 HEHE😀 😀 😀
i think that the water in the coffe can wil get dirty ( in the best scenario), it also may leak and set a fire in your house!!!
😀 😀 😀 HEHE😀 😀 😀
Remember building the 100 inch TV? Remember sticking a finger in front of the fresnel but the image was still there? xblocker is right about why we wouldn't have blocked pixels.
I'm having this problem too. How does using a double convex lens fix this? I have a double convex lens and when I try it out, it's even more blurry at the edges.
I can't 1/2 of the outer edges of the lens, well, I can but it gets too dim when I do that. Using a correction lens can be difficult because I don't know the right lens that I would need.
Are there any other solutions to the spherical abberations?
Im glad I heard from you guys about the halogen 500W with reflector lamp. I almost bough it but didnt cause I wasnt sure about how much heat that thing would produce.
undream
Just a suggestion, buy some mirrors and use them. That would reduce the size of your projector a lot.
undream
Just a suggestion, buy some mirrors and use them. That would reduce the size of your projector a lot.
Satellite dish won't work with my idea:
1) A sheet of mylar on a satellite dish will reflect light, but the picture would be unviewable. Try shaving in a mylar ballon reflection.
2) Silvering the dish would be useless as well. Radio=big wavelength, light =small wavelength. Once again, the image would get all screwed up.
I'm looking into building a lazy susan to pour glass in and spin slowly in a kiln to minimize grinding and polishing times. Still lots of things to figure out. I'll probably find some amature astronomer that will let me do some tests with their reflecting telescope. I'm still working on my on board computer for my truck so it may be a while before I can devote a lot of time to this. It's fun to think about though. Imagine projecting a GPS image on the road in front of your car as you drive at night. I'm sure it would be illegal, but fun to imagine. What I really want to do is play movies a hundred feet tall on a canyon wall during the campout that follows a day of off roading.😀
1) A sheet of mylar on a satellite dish will reflect light, but the picture would be unviewable. Try shaving in a mylar ballon reflection.
2) Silvering the dish would be useless as well. Radio=big wavelength, light =small wavelength. Once again, the image would get all screwed up.
I'm looking into building a lazy susan to pour glass in and spin slowly in a kiln to minimize grinding and polishing times. Still lots of things to figure out. I'll probably find some amature astronomer that will let me do some tests with their reflecting telescope. I'm still working on my on board computer for my truck so it may be a while before I can devote a lot of time to this. It's fun to think about though. Imagine projecting a GPS image on the road in front of your car as you drive at night. I'm sure it would be illegal, but fun to imagine. What I really want to do is play movies a hundred feet tall on a canyon wall during the campout that follows a day of off roading.😀
ZeCo,
I was considering it. But, then I'd end up with a main box that is much taller. dunno if thats better or not. I guess its personal preference.
I was considering it. But, then I'd end up with a main box that is much taller. dunno if thats better or not. I guess its personal preference.
xblocker,
thank's for your advice.
You said that your OHP has an objective with 2 positive meniscus lenses, is it identical?
is each of the lens doublet lens or just single lens?
With that lenses, do you have problem with blue and red shift on the projected image color?
Is it crisp and sharp evenly up to 4 edge of the image?
I plan to use 2 PCX lens with fl=318mm and 1 DCV lens with fl=-230mm, total fl become around 540mm, what do you think? does it good? Do you think this setup still have both abberation problem (spherical & chromatic)?
I hope all my questions don't bother you.
Thank's a lot.
Undream,
your setup almost final, I think, and you only use single PCX lens, since my setup use single PCX lens too, I wonder how's your projected image?
I got some abberation problem as I mention above, do you get that problem too? Please tell me about your image.
thank you.
thank's for your advice.
You said that your OHP has an objective with 2 positive meniscus lenses, is it identical?
is each of the lens doublet lens or just single lens?
With that lenses, do you have problem with blue and red shift on the projected image color?
Is it crisp and sharp evenly up to 4 edge of the image?
I plan to use 2 PCX lens with fl=318mm and 1 DCV lens with fl=-230mm, total fl become around 540mm, what do you think? does it good? Do you think this setup still have both abberation problem (spherical & chromatic)?
I hope all my questions don't bother you.
Thank's a lot.
Undream,
your setup almost final, I think, and you only use single PCX lens, since my setup use single PCX lens too, I wonder how's your projected image?
I got some abberation problem as I mention above, do you get that problem too? Please tell me about your image.
thank you.
The image looks very good. Now, it might be because it is still fairly dim, but, I don't notice it being less bright on the edges/corners. I dont know, maybe when I get my new lamp i will notice it more.
What kinda lamp are you using, Gunawan? I noticed a while back that you are using a smaller PCX lens than me. 4 1/2" rather than 5 7/8". Think that could make a difference?
What kinda lamp are you using, Gunawan? I noticed a while back that you are using a smaller PCX lens than me. 4 1/2" rather than 5 7/8". Think that could make a difference?
Undream
I use 300w halogen lamp with double ended, but it's only for testing the lens, for final setup I'm going to use MH 200W to 300w (around 20.000 lumens) with double ended too.
About the lens, I use smaller lens than yours and I got that abberation problems. I think it is not good quality lens.
You said that your image bright up to the edge, but is it still sharp compared with middle area?
I will wait your MH lamps setup and please tell me the result, thank's.
The Xung
I got the conclusion about spherical abberation from:
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/aber.html,
"The use of symmetric doublets greatly reduces spherical aberration."
and this:
http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln/u13l3g.html,
"Then a cover was placed over the outer edges of the large demonstration mirror; the result was that the image suddenly became more clear and focused."
when you use 1 lens with fl. let say 12", then put another lens, it will become doublet, and if you want total fl. same as first lens, you need 2 lenses with fl.=24".
I got better result with covered 1/3 of the lens (lens dia. 4,5"), I didn't test with double lens, because I have 1 lens only.
Hope this will work for you too, and don't forget telling us your result.
see you.
I use 300w halogen lamp with double ended, but it's only for testing the lens, for final setup I'm going to use MH 200W to 300w (around 20.000 lumens) with double ended too.
About the lens, I use smaller lens than yours and I got that abberation problems. I think it is not good quality lens.
You said that your image bright up to the edge, but is it still sharp compared with middle area?
I will wait your MH lamps setup and please tell me the result, thank's.
The Xung
I got the conclusion about spherical abberation from:
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/aber.html,
"The use of symmetric doublets greatly reduces spherical aberration."
and this:
http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln/u13l3g.html,
"Then a cover was placed over the outer edges of the large demonstration mirror; the result was that the image suddenly became more clear and focused."
when you use 1 lens with fl. let say 12", then put another lens, it will become doublet, and if you want total fl. same as first lens, you need 2 lenses with fl.=24".
I got better result with covered 1/3 of the lens (lens dia. 4,5"), I didn't test with double lens, because I have 1 lens only.
Hope this will work for you too, and don't forget telling us your result.
see you.
ChuckReese,
is that the only way to get the perfect image free of spherical and chromatic abberation?
If I use 2 identical dcx lens, does it still have spherical abberation? (not chromatic).
is that the only way to get the perfect image free of spherical and chromatic abberation?
If I use 2 identical dcx lens, does it still have spherical abberation? (not chromatic).
I think the only way to get totally rid of spherical aberation is to use an aspheric lens, but using two pcx lenses back to back also does a good job. (Keep in mind that I have not tried any of this yet, but this is what I gather from reading the tech docs.)
The only way to get rid of chromatic aberation is to use a doublet or triplet, so to get rid of both, you need two of these back to back. I think a good OHP will already have optics that takes care of this so maybe you should try to salvage one.
The only other way I know of to get rid of these aberations with an elliptical mirror. If you have an elliptical mirror with a 32" focal length, then you can get 4x magnification of an LCD at about 10 feet without the need for any projection optics. This might be another way to go, but I am still trying to decide it I will be able to make the mirror for reasonable cost and effort.
CR
The only way to get rid of chromatic aberation is to use a doublet or triplet, so to get rid of both, you need two of these back to back. I think a good OHP will already have optics that takes care of this so maybe you should try to salvage one.
The only other way I know of to get rid of these aberations with an elliptical mirror. If you have an elliptical mirror with a 32" focal length, then you can get 4x magnification of an LCD at about 10 feet without the need for any projection optics. This might be another way to go, but I am still trying to decide it I will be able to make the mirror for reasonable cost and effort.
CR
i started thinking about the money i put in to this and the posible way of my water idea leeking, flooding etc( for instant the light source gose out but the fans are still on,maybe the glass containing the water, breaks due to hot glass cold air from fan will break it)? S.O.L./fu*ked. so im setting that aside for now(it will be last resort maybe). now i have big doubts on my shity light source ( G.E. reader lamps about 5000 lums. i have 4 ) it had potential for the water idea (just had that feeling) but i dont think its going to work for the strait line setup im planning. so can some one help me out with a light source. and dose anyone no how the mh59 works i heard it dosee 40,000 lums. thanks
😀 😀 😀 😀
😀 😀 😀 😀
Gunawan,
These two meniscus lenses aren't doublets, each has a fl=630mm, diameter=80mm. They are identical. Without a panel on OHP's stage, depending of throw distance there is moderate blueish or redish border. But this the case with all OHPs and can corrected by slightly changing the distance between bulb and fresnel.
As i said in another post, image has an overall sharpness, edges are minimal dimmer as the center.
Refering to your lens plans, i would say, this depends of lens quality and glass refraction index.
BTW, my calculating result gives me 515mm fl total (1/fl total=1/fl1+1/fl2+1/fl3)
Hope this helps!
xblocker
These two meniscus lenses aren't doublets, each has a fl=630mm, diameter=80mm. They are identical. Without a panel on OHP's stage, depending of throw distance there is moderate blueish or redish border. But this the case with all OHPs and can corrected by slightly changing the distance between bulb and fresnel.
As i said in another post, image has an overall sharpness, edges are minimal dimmer as the center.
Refering to your lens plans, i would say, this depends of lens quality and glass refraction index.
BTW, my calculating result gives me 515mm fl total (1/fl total=1/fl1+1/fl2+1/fl3)
Hope this helps!
xblocker
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