A colleague and I needed a few inexpensive projectors for a project we are working on so I bought the Lumenlab projector guide and since I've been collecting materials and lurking on the forums trying to absorb some of the collective experience of the members.

After receiving my lenses from the recent shipment I took a stab at building my own projector. The experience was positive and I'm very impressed with the results.

Thanks to Brainchild and the other researchers on the forum for their ongoing efforts.

Here's a picture of my completed projector. I'll post a description as my contribution to the common good. Any comments or suggestions for improvement are welcome.

cool, VERY nice work !!!!!!

does you focus mechanism work fine ? i take that front is a focus right ?

anyway, please post some pictures of the results.


thanks,
wackoo

Groovy focus adjustment

- The box is made of MDF cut as per the dimensions in the guide and held together with IKEA-bookshelf-style furniture screws.

- The front panel can move back and forth in four two-inch long slots shown in the previous picture. I've tested its ability to focus projected images from 6 feet to 13 feet wide.

- On the right side I have a panel with two switches (fan and light/LCD) and an electrical outlet. (The outlet has proved suprisingly handy - in the previous picture my camera is plugged in to it because my batteries were dead).

- The top is held on with a continuous (piano) hinge and the ventilation slot in the top is filled with blue air-conditioner stuff to block light escape.

- The following picture shows the light mounting which is as far back as I could make it (I put the mogul base right in the corner and angled the light slightly forward to center it). I put flashing on the rear panel to protect the MDF since my light is very close to it. The ballast and fan are located in front of the electrical panel and are also protected with flashing.

Looks great but seriously consider switching to the new lamp. You could mount it horizontally and the output is substantially higher.

Here's a picture of my lens assembly - the picture is sort of hard to make out and deviates a bit from the guide a bit so I will describe it.

- I experimented with the lens placement using a transparency as was suggested in one of the other topics. That was a great suggestion!

- Another great suggestion was not to let the fresnel lenses get dirty - unfortunately, I read that one too late! The paintbrush idea, however, was great for getting sawdust out of the grooves.

- I couldn't get the image to focus without holding my projection lens in front of my box a couple of inches (this is consistent with others' results). Rather than build a box in front I found that if I moved the collector lens in front of the transparency I could focus without changing the dimensions of my box. This seemed to be the path of least resistance.

- The projected image has some fresnel groove marks on it if you look hard but they seem to be not much more noticable than the LCD screen door effect.

- Since my collector ended up ahead of my LCD I've hung it from a coathanger to provide the automatic keystone adjustment (which works great by the way!). In this picture the projector was tilted at about a 12 degree angle.

- My LCD is a 15inch Liquidvideo taped into its metal frame. As per some suggestions in the monitor stripping topic I photographed and logged every step of the teardown so I can put my monitor back together again someday. I'd like to replace the LCD with one from a broken monitor eventually and use the LiquidVideo on my home PC so I made no modifications to the monitor parts during installation. With a groove cut into the bottom of the box, the metal frame fit nicely into the standard dimension box.

- Instead of mounting the collimator lens directly onto the tempered glass I mounted it onto another piece of glass separated from the tempered glass by an air gap. I did this because I didn't know the specs of the fan I used (which was out of an old OHP) and I wanted an extra layer of safety. I small hole in the side of the box lets me insert a meat thermometer. The temperature in the air gap levels out to about 90 degrees. I've had the projector running for over 10 hours with no overheating problems yet.

- My glass panes are held in with small blocks of scrap wood (This works but doesn't look so good).

- The LCD is held in on one side with a piece of quarter-round and on the other side with a screw butted up against the edge of the metal frame.

Brainchild, I bought my lamp literally the day before you found the new one. I will probably try to upgrade soon. Does it produce a noticeably brighter picture?

YES

thanks for the tips !!

Ookpic,

Very nice, can't wait to finish mine!

I like your idea to hand the fresnel for keystoning by the coathanger.That would allow it to adjust itself and also be moved around in the box easily if need be.

I've had a hard time getting a decent screen picture out of my digital camera (it makes a better video camera) but here is a picture of a scene from Finding Nemo.

It was taken on a 6 foot wide screen made out of a bedsheet (I'm hoping to get a better screen). The brightness looks similar to the commercial digital projectors where I work but it is hard to tell without seeing them side-by-side.

I also think your going to see your focus design used on some other projectors. I bet it works pretty well.

QUOTE (Stick @ Mar 15 2004, 11:52 PM)



Thanks Stick. I have 2 inch long grooves cut in the box sides in case I want to move it around. I've found, however, that I can't move it too far forward or part of the image falls outside of my projection lens.

Thanks OKflyboy,

I hope you get your FFC fixed - mine is still intact but it would be nice to know it can be fixed just in case.

How far away from the panel does the keystone fresnel hang and how much of an angle do you think it can handle.
By the way you've done agood job with your project! Thanks for posting it and adding pics. I check about every evening for new content and I really enjoy the personal project posts.It amazes me how many good yet different ideas everyone has.

Thanks! Me too!

So far I've been normally keeping the collector fresnel (pivot point) about 2 1/8 inches from the LCD panel.

I wish I understood more about optics (I've been planning to read a book on the subject). Any information I have outside of what is in the Lumenlab Guide and these forums comes from naive experimentation. For what it is worth, here is what I think I've observed (perhaps someone who knows more about optics can explain it):

At a distance of 2 1/8 inches, the maximum angle my projector can be tipped while maintaining keystone correction is a bit over 12 degrees at which point the bottom of the fresnel comes close to touching the LCD panel. I have been using the projector on a stand and this provides more than enough tilt for my purposes. I haven't noticed any affect on focus as the projector is tilted.

I have moved the collector lense out to 3 3/4 inches from the LCD panel. To retain focus the projection lens had to be moved in (I didn't measure how much). This provided more clearance for the collector fresnel to tilt and the keystone correction could be maintained until a bit over 20 degrees. Around 20 degrees I had to tape down the coathanger so it wouldn't slide toward the LCD panel. I didn't check to see if the corners (or top) of the image were being clipped.

Hope this answers your question.

A self-correcting, suspended fresnel for keystone correction? Brilliant!

thanks H_ank,

Here's a closeup in case anyone else wants to use this approach.

The coat-hanger wire runs from one end to the other.

The green border on top that looks like a folder binding is actually called "Vinyl Trim Cap" from Home Depot and is used with steel landscape edging.

The coat-hanger and trim cap are held on more firmly with binder clips (these seem to be right up there with duct tape for utility). Initally I used only binder clips but it was hard to get the lens to hang straight down with only the clips because of the shape of their cross-section. The trip cap fixed that problem.

I added the metal brackets later. I salvaged them off of an old OHP. Their purpose is to keep the coat-hanger from rotating. My guess is that they would not be required in most designs. They became necessary in my design because I wanted to raise the fresnel lense a bit to keep it from hitting the Liquidvideo circuit board (which I was too timid to bend all the way to 90 degrees). When I raised the lens by bending the coat-hanger ends down, the coat-hanger tended to rotate and the lens ended up lower then when I started. The metal brackets fixed that.

look great i hope i can make mine that nice.. just one question about yours..the collector that is mounted with the coathanger for automatic keystone did u use a glass there or just the lenes? thanks for your time and again great work

For the collector I just used the lens - no glass.

Looks great!!!

Great Job! I like the adjustments, gives me another Idea on my focus/zoom lens, basically taking out the focus part, makes building a zoom much easier.

Brain > the triplet you sell (still waiting on mine) can disasemble? I haven't got a look at it yet...but I have been playing around with my zoom lens from my camera....getting a feel on how they work.

Even if they do come apart, I'm not too sure you would want to. The lens is perfectly aligned and if you build another out of the three lens' then you could come into the issue alignment and that could be difficult to fix on the fly.

Yes they come apart easily via the back threaded ring. There are small plastic spacers that hold the lenses in position so care should be taken to preserve their locations and orientation. Also the negative lens (middle lens) edges are very susceptible to chipping so be careful. I'd definitely encourage anyone wanting to try to take the lens apart; to get a better understanding of how it works and to experiment with the single optics individually. Just be careful;)

I was thinking of buying an extra triplet to do my tests on. I just have to figure out some figures of a formula so I know how it will effect the projection.
I want to use exsisting triplet lens and expand it on a new barrel so that anyone that has purchased the triplet already or wants things to fit in there box easy, could do so.

Andrew,

I couldn't figure out how to reply to your e-mail so I'll post the answer here - hopefully you'll notice it - wherever you are !



I saw this suggested by Lamps March 6, 2004, 04:08am under the topic "Stick's Projector". Hopefully if you read the suggestion in the context it was written my reference will make more sense.

Cheers ...

Great handiwork! What kind of bolts did you use there for your focus mech. ?

psy.

Might be a while before you get an answer, last time Ookpic was here was almost a year ago.

Dang! oh wells.


psy.

Psy,

It has been a long time since I've logged into the Lumenlab forum. I received an e-mail notification about your post. I figured that this topic would have been buried so deep by now it would have been cleared off their server! - Anyway, my family and I are still enjoying our projector.

I bought the bolts I used for the focus mechanism at Home Depot. I think they were called "furniture bolts". They are similar to the bolts you would get in some of the put-it-together-yourself furniture from IKEA.

Good luck.

Ookpic