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Opaque Projector
Here it is. No. 2 in my BelAir series of retro-feel homebuilt AV equipment (see No.1). I used a surplus copy machine lens to make this opaque projector for use as a drawing aid. (See this post for background info and plans) .
The projector is essentially a wooden box with with a lens, internal lighting to illuminate reflective copy, and a mirror to flip and invert the image so that it is projected right-reading on the screen. These projectors are great tools for enlarging images when making paintings, posters or other such artwork.
Materials
I was able to use quite a bit of scrap and on-hand materials for this project, which is always satisfying. I made most of the box out of some nice 1/4 inch plywood that I had lying around. The front panel is 1/2 shop grade plywood, also scrap. The mirror has been kicking around the shop for years, as have the ceramic light sockets. I made the lens holder from an empty cocktail peanut can, epoxied into a hole cut in the front panel.
I purchased the two 23 watt fluorescent bulbs, which are supposed to have the same light output as 100 watt incandescents. I also had to purchase the chrome toggle switch, the wrinkle paint, and the stylistic embellishments.
Finish
I painted the cabinet with black wrinkle paint from Plasticote before installing the chrome (1966) BelAir script and ruby red Fender amp indicator jewel.
Focus is achieved by simply twisting and pulling the lens in and out.
I still need to paint the bottom edge of the cabinet and make some reflectors for the lamps.
I got rid of the dimestore mirror and installed a trapazoidal front-surface mirror. If I were just building an opaque projector I wouldn’t worry about the ghosting that you see with a rear surface mirror, but since I have video projection ambitions for this project, I went ahead and upgraded the mirror.
To get a nice snug fit inside the peanut can lens holder, I wrapped the lens with several turns of black yarn. This makes for a nice snug fit, and keeps any light from leaking through.
Results
I’m pretty happy with it. I didn’t spend too much building it - less than I would have spent on a low-end commercial unit, which can typically only handle copy under 6 inches in size. The projector works great. The copier lens can take in really big copy. The BelAir handles 9 1/2 x 12 inch originals, looks cool, and was fun to make.
Future
If I can find a cheap portable DVD player with an LCD monitor, I want to make this into a movie projector.
UPDATE:
Following in the footsteps of Mr. Jalopy, I have spent lots of time on the immensely rich Lumenlab forum, and I am gathering parts to build the video projection base unit.
This is a beautiful thing. Looking forward to seeing the next phase. Is that BelAir script the same as the BelAir script on your entertainment center? What is the source of this one?
Nice
Mcewanj
I have a 19″ LCD panel that I’d be happy to give you for building a projector. The backlight is dead (pretty sure it’s the inverter) but the panel itself works as tested using a flashlight.
Hey Matthew,
Nice thanks for the offer, but from what I can tell, I need a smaller panel. Something like a 7 inch would be ideal. But I have more research to do.
Cheers,
steve
The LCD projector, has already been done, and its on sale for $500…
You want the LCD that comes with a TV, not a laptop version…as no one will give you the Pin outs and control card for the laptop.
Hey, any pics of the output of this? Would love to see how it works!
Hey Liam,
It works pretty well as opaque projectors go, but the output is quite dim. It really needs to be used in a completely darkened room, especially at higher magnifications, but that is par for the course with a reflected light projector.
Since these photos were taken, I have painted the inside black to reduce stray light, and added reflectors to the lamps. This probably doubled the brightness of the image.
I’ll post an update when I start the video projector leg of the project.
fantastic. the crinkle paint was a nice touch. Can we see it in action?
hey! I really like the look of this project! I have a project I’m working on and i’m trying to find the same wrinkle coat finish… can you tell me where you found it? I tried home depot, lowes, and ace hardware… no dice.
by the way, I’m in seattle too, one of these days maybe we’ll meet up, I have a bunch of projects I think you’d appriciate based on what’s here on your blog.
Hey Curt,
You can find the wrinkle paint at auto parts stores. I got mine a Autosport on Aurora, just north of Greenlake.
cheers,
steve
great! that’s right by my workshop, so I’ll swing in this weekend and grab some! thanks!
Hi I am a teacher and I need make one for my class, you can send me the messures thaks
Great work! This has inspired me to build one, too. For my purposes, the commercial ones require too much fiddling around (making sure the picture is reduced to such a tiny size and all), and they all seem to be made of plastic. I want something large and sturdy, without having to spend megadollars.
Many thanks!
I purchased one of these lenses because I troll AS&S and, frankly, the lenses are just plain awesome (I plan to buy several more if money allows). I then came across your site because I also had the idea to build an opaque projector and Google (via Make) told me about your project. I was really happy to see the PDF link you gave us, but I think it has caused me more problems than I had trying to work it out on my own.
I built a little proof-of-concept projector out of the lens, a fluorescent light (with work-light-type reflector), and an old cardboard box. It worked beautifully (though since there was no mirror everything was backwards/upside down). I decided to build a for-real box based on my stunning success. This was about the time I found your article, so I dug through the PDF you recommended and decided to go with the plans on page 14 (though it claims pg 12). I had to scale them up a little because our lens was much larger and my mirror was a good bit larger as well (8″ x 8″). Lo and behold it was worthless. I can do the math and the focal length of the lens lines up pretty well with the “document” being shown, the light from the lamps isn’t directly hitting the lens (because of blocking), and AT LEAST as much light is hitting the surface of the “document” as in my PoC. However, most of the light was lost inside the box and what light DID come through the lens was impossible to focus into an image (note: I haven’t painted my box yet).
I guess what I’m asking is what the dimensions of your box are? I’m not sure what’s different from yours to mine (in terms of focal-length, etc), but I’d love to know (even rough) dimensions. Also, what did you use for reflectors?
Thanks for your time and great article,
-Jeremy
P.S. your CAPTCHA is effectively worthless against real SPAMmers… you should check out reCAPTCHA.
Aw hell… I’m on a posting spree so I’ll throw this out there. I had the idea of using black felt (as opposed to yarn, like you did) and it happens that if you give the lens a few turns of black felt it fits nicely into a piece of 4″ black PVC from any “home improvement” store. I liked this becaue I could glue/tape it down instead of having to tie it down (and I hadn’t thought of using yarn).
Hello!
I am constructing one for myself and I wondered if you could give me the measurements of your box? I am trying to figure out at what angle to put the mirror.
Thanks a ton!
Hello!
I am constructing one for myself and I wondered if you could give me the measurements of your box? I am trying to figure out at what angle to put the mirror.
Thanks a ton!
it did helped me a lot with our science fair.
I don’t see the lens everyone is talking about. Any idea if it’s the same as the ones showing now?
(http://www.sciplus.com/category.cfm/subsection/21/category/188)
ie., 27379 F:4 LENS 28mm F:4
I’d love to try this, but I’m unsure where these lenses went.
HELLO, I’VE HAD THIS OPAQUE PROJECTOR PROJECT IN THE
BACK OF MY MIND FOR A FEW MONTHS, AND I CAME ACROSS
YOUR VERSION. CAN YOU GIVE ME A CLUE ABOUT HOW TO
GET THE LENS. IM IN PUERTO RICO AND THERE ARE NO JUNK
SHOPS HERE LIKE I USE TO HAUNT WHEN I LIVED IN CHICAGO.
THE LARGER 91/2″ X 12″ IS REALLY A GREAT ADVANTAGE.
THANKS MUCH, RETIRED TOOL MAKER
JIM D.
Hey Jim,
Well, I checked my source and they are sold out. Just search the web for “surplus copy lens”.
steve
Hi, I just stumbled onto you web site and I like how you built your opaque projector. I recently bought a high end opaque projector for almost nothing because it didn’t work. Turned out it was just a loose wire! . I plan to use the projecter for tracing photos to canvass so I can do some oil paintings. I would rather have the projector overhead projecting an image downwards on a flat table rather than projecting it onto a wall. I was thinking about building some sort of wooden framework to hold the opaque projector up in the air and then using a mirror to cast the image downward. I am afraid that if I just mount the projector facing downwards that it might build up too much heat because it isn’t designed to function like that. Any thoughts on this? Is there a better way? Thanks. Herb
THANK YOU so much for this! My budget will not cover the expense of an opaque projector and I really want one. I teach kids with learning disabilities and research shows that an opaque projector, used with other strategies, helps develop skills in reading. I can’t wait to make it and get it to my classroom!
I built an opaque project about 35 years ago that I have just recently set up again. Because of changing needs I would like to increase the magnification of the final image. I am wondering how to do the calculations to determine what lens to look for. Any help you can provide would be appreciated.