Hey guys...
Ok, I have a standard SEGA Game Gear with standard LCD and by a proccess of experimentation, i found that (though inverted and quite dim) the image can be projected on to a wall using just a standard lens from an old slide viewer like the ones with the batteries and a bulb and lens.
But my question is that i am interested in DIY projection (hopefully on an old 14" CRT TV soon) and wondered how the fresnel lenses come in because if the small, regular lens from a slide viewer acts as a projection lens, then why do i need a fresnel lens?
The lens is about the size of the LCD (3" x 2.5")
Oh and also, does anyone have any radical ideas on fixing the inverted image?
Cheers, DBeen
Ps: I have also used this lens to project an image of my hifi's LED spectrum analyser to quite good effect, though that was also inverted (not too much of a problem) and relatively dim.
Ok, I have a standard SEGA Game Gear with standard LCD and by a proccess of experimentation, i found that (though inverted and quite dim) the image can be projected on to a wall using just a standard lens from an old slide viewer like the ones with the batteries and a bulb and lens.
But my question is that i am interested in DIY projection (hopefully on an old 14" CRT TV soon) and wondered how the fresnel lenses come in because if the small, regular lens from a slide viewer acts as a projection lens, then why do i need a fresnel lens?
The lens is about the size of the LCD (3" x 2.5")
Oh and also, does anyone have any radical ideas on fixing the inverted image?
Cheers, DBeen
Ps: I have also used this lens to project an image of my hifi's LED spectrum analyser to quite good effect, though that was also inverted (not too much of a problem) and relatively dim.
my advice:
stop before you even start. Dont waste your doing to lense/box method. It will only lead to frustration. Grab yourself a decent panel and a nice overhead projector and start from there. You should be extremely pleased with the results.
spend an hour or so at these forums and familiarize yourself with whats good and what isnt. 🙂
stop before you even start. Dont waste your doing to lense/box method. It will only lead to frustration. Grab yourself a decent panel and a nice overhead projector and start from there. You should be extremely pleased with the results.
spend an hour or so at these forums and familiarize yourself with whats good and what isnt. 🙂
StrayPixel said:
actually, it should be what works and what absolutely will not *cough*crt/fresnel*cough*😉
Yeah, but I'm on a tight (non-existant) budget here guys... The lens/crt tv thing i tried again last nite, and it was ok in pic quality but fuzzy edges ('tis a magnifier lens). It is ok in my (miniscule) experience to experiment with and since unless I win a lottery I can't afford a projector and lcd so the Game Gear thing was the closest available alternative to try.
-edit:
Do fresnel lenses solve the fuzzy edge thing?
-edit:
Do fresnel lenses solve the fuzzy edge thing?
Damn. So how does it work then?
Going by what I (think I) know, I would still need the smaller lens that I have now, but in unison with a fresnel, right?
Current:
| TV | ----> Projection Lens
The configuration that I guess i need:
| TV | ----> Fresnel ----> Projection Lens
Please correct me if I'm wrong!
Going by what I (think I) know, I would still need the smaller lens that I have now, but in unison with a fresnel, right?
Current:
| TV | ----> Projection Lens
The configuration that I guess i need:
| TV | ----> Fresnel ----> Projection Lens
Please correct me if I'm wrong!
stuff n' junk
First of all,
I concur with the above posts...a TV emits enough light to brightly light it's tiny little screen..and maybe put a little glow on your face...it will not make for a good projected image of any size at any brightness level that is tolerable...
I will, however, go a little further to try and help you understand the fresnel and why you are getting backwards stuff....
FIRST!: the fresnel is 2 lenses smooshed together..the bottom one takes the light and spreads it evenly, the top one focuses it back on the lens at the top of the OHP or the "projector lens" as you said.
Now..just a couple things I did that might help you figure out your backwards situation...If you take an OHP with the fresnel lens in it, pull the mirror off the top and point it sideways straight at the screen you will get an image that is both upside down and backwards...if you roll the OHP 180 you will be right side up but still backwards...so the mirror is necessary when dealing with an OHP...i hope you can take that and apply it to your question.
First of all,
I concur with the above posts...a TV emits enough light to brightly light it's tiny little screen..and maybe put a little glow on your face...it will not make for a good projected image of any size at any brightness level that is tolerable...
I will, however, go a little further to try and help you understand the fresnel and why you are getting backwards stuff....
FIRST!: the fresnel is 2 lenses smooshed together..the bottom one takes the light and spreads it evenly, the top one focuses it back on the lens at the top of the OHP or the "projector lens" as you said.
Now..just a couple things I did that might help you figure out your backwards situation...If you take an OHP with the fresnel lens in it, pull the mirror off the top and point it sideways straight at the screen you will get an image that is both upside down and backwards...if you roll the OHP 180 you will be right side up but still backwards...so the mirror is necessary when dealing with an OHP...i hope you can take that and apply it to your question.
Ok... Here's an idea I had and rubbished a while ago, but never tried it...
(1) Take one TV... turn it on it's back...
(2) Take one OHP... Cut the bottom off just below the fresnel...
(3) Place said OHP on top of said TV...
(4) Watch TV.
This seems too easy, but would any part of it work?
Even if the plan was modified slightly?
Though I guess that the fresnel would have to be about 6-10" from the TV screen?
-edit:
Also, the TV I am using does have sufficient brightness to project with all the settings turned up (contrast, bright etc...)
(1) Take one TV... turn it on it's back...
(2) Take one OHP... Cut the bottom off just below the fresnel...
(3) Place said OHP on top of said TV...
(4) Watch TV.
This seems too easy, but would any part of it work?
Even if the plan was modified slightly?
Though I guess that the fresnel would have to be about 6-10" from the TV screen?
-edit:
Also, the TV I am using does have sufficient brightness to project with all the settings turned up (contrast, bright etc...)
My thoughts
First of all Dickerbean, if you want to go pure cheap-o don't even mess with a fresnel. If you bought one of the 150" fresnels off ebay or from a spam, then you've not got anything of any use. (trust me, I have two of them)
What I did with a TV was to use a projection lens. I just searched on ebay for projection lens. I bought one that was a barrell with a lens on each end and I didn't even know what it came out of. Just that it was a projection lens. I paid all of $5 for the lens, and $6 for shipping. I put it in a box just like the ones described for those cheap-o fresnels, and I was able to project my 13" TV at almost 100" and I had a good clean picture on all edges. I was actually quite impressed with myself. Knowing what I know about how TV's work, I was able to rotate and invert the picture by swapping some wires around inside the TV.
Everyone I showed it to was pretty impressed. But not like they were when I got a LCD panel and plopped it on my OHP.
First of all Dickerbean, if you want to go pure cheap-o don't even mess with a fresnel. If you bought one of the 150" fresnels off ebay or from a spam, then you've not got anything of any use. (trust me, I have two of them)
What I did with a TV was to use a projection lens. I just searched on ebay for projection lens. I bought one that was a barrell with a lens on each end and I didn't even know what it came out of. Just that it was a projection lens. I paid all of $5 for the lens, and $6 for shipping. I put it in a box just like the ones described for those cheap-o fresnels, and I was able to project my 13" TV at almost 100" and I had a good clean picture on all edges. I was actually quite impressed with myself. Knowing what I know about how TV's work, I was able to rotate and invert the picture by swapping some wires around inside the TV.
Everyone I showed it to was pretty impressed. But not like they were when I got a LCD panel and plopped it on my OHP.
Ok you really don't need a big budget to do DIY. my first lcd panel was only 4$ on ebay and i got to pick it up. look on ebay for the things you need because sooner or later a good deal will fall in your lap! and we are here to help you.........Bob
Ok, any advice on what type of lens works specifically? And once again any radical ideas on inverting (correcting) the image?
Well, you can flip the TV upside down. Unfortunatelly, this isn't to good for the TV, but for a 14" it shouldn't hurt it too much, just never do this with something much bigger. You can use mirrors, but that makes you loose more light, which is already in short supply. There's a way to switch the image by swapping some wires inside the TV, but ubless you're certified in such things, opening a TV is VERY DANGEROUS, and SHOULD NOT be attempted.
I agree that DIYing doesn't cost much. Get a cheap panel for $50 on eBay(my Spectra was $45 and works very nice), plop it on an OHP and you'll really have something amazing.
I agree that DIYing doesn't cost much. Get a cheap panel for $50 on eBay(my Spectra was $45 and works very nice), plop it on an OHP and you'll really have something amazing.
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