4 inch LCD and Slide Projector

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I would like some input please I have just purchased these two and was thinking about either ground up design or maybe using the existing Slide projector and mounting panel inside.I also have a stripped 3M overhead with a 250watt light source Fresnels etc. So could utilse parts if necessary Looking for a 60 inch projection primarily for DVD.I know there is a thread with slide projectors but it seems to have gone stagnant?My budget is blown from previous disasters (you,ll see in my other posts) so want to get this one right.


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With the slide projectors there lenses are set up to use slides or what not that are smaller than 2.1/2 inches, so I don't think that they would be large enough to cover your 4'' screen. The easiest would be to use your ohp and mount the lcd on top of that. Look around there was one user that mounted a playstation screen on the ohp and got some decent results after some tweaking. If you decide to build the pj using the parts from the ohp you will have to cut the fresnels down to size, and re-wire the lighting unit. I personally would first mount it on top of the ohp, because that is the fastest method to getting a working projector unit. And then you can go from there.
Medium Format?

Hey Tactix thanks for the reply can you explain what is meant by Medium Format?

Not sure if mine meets that criteria?

I was tossing up whether to strip the projector seeing how my panel is 4 inch and the projector is made to take 2 inch slides.

Do you have a Slide projector in mind?
need lens for my medium-format

I've been thinking along the same lines... small LCD with a medium-format slide projector.

I bought a HipGear controller last summer for the 2.5" LCD, but I would like to see a higher res 4" LCD work for the project. The reason being that I don't think we'll see a res increase in the small LCDs before they all shift to OLED.

As for the slide projector, I just picked up a medium-format last week off eBay for less than $15 (US) and about the same again in shipping. Unfortunately, the seller neglected to reveal that the triplet was smashed beyond repair (he was nice enough to include pieces of the lens in a separate box...?!). Otherwise, the other optics are good, and the housing is a beautiful size for a portable projector. The out-of-production lamp will have to replaced with something more common (halogen?).

For those who are more knowledgeable: Any recommendation for finding a suitable replacement lens? (besides eBay, that is... I'm still licking my wounds). I believe the lens is standard for slide projectors: coated anastigmatic; f/3.5; and the barrel is 127mm (5.0") in length, 38mm (1.25") in diameter.

Advice gladly received!
It's a workable size and a nice design, but the unit is solid steel construction and it's going to take much effort to mod. But there is no beating that the two condenser lenses are a ginormous 4+" in diameter!

I haven't decided how best to power the light engine. The original bulb for the unit was 300 watts and the unit contains a substantial propeller of a fan to draw the heat off---though I may replace this with a more efficient squirrel cage blower. There is no room for anything that requires a ballast, and the one little pocket of space available will be filled with the LCD panel's AC->DC wall wort.

In another thread, I believe I read that resident expert Guy Grotke recommends halogen for small projectors when MH wasn't a possibility. Also, the lateral design of the light box, the placement of fan/vents, and the presence of an integrated reflector defeat the necessity of a dichroic lamp or any single point with reflector. The original lamp is a single point (bulb type), but, in my estimation, a two point lamp looks to be better suited. Albeit, I am completely new to this and absolutely open to suggestions. I am even willing to scrap the original light box if it comes down to a matter of practicality.

First things first, though... without a lens the project cannot get off the ground. I mentioned it was a triplet, but I may be showing my ignorance. The lens unit is comprised of a concave sandwiched between two convex lenses. The screen-facing convex is missing and the concave is splintered. The condenser-facing convex is fine. It is theoretically possible to reconstruct the barrel from the broken pieces, but I am clueless as to removing the permanently-bonded and cracked concave. I am also at a loss on the focal lengths should I try to buy new lenses. Replacement of the whole unit seems a better option.
I received my projector and LCD yesterday tested both all good.I dont have any hope of fitting this panel inside the projector so have begun stripping it down I,m going to build a "Pico" style enclosure.One thing I did notice is the heat these lights give off man its intense! For its size I was really impressed at the res from the LCD and the A/V style connections make it easy.The lens will probably have to go they just dont have the spec to pull off a decent picture but I,ll give it a go.I,ll post pictures as I go along as I,m recording everything.
Looking back over the posts I just realize I made a serious error in measuring. The lens barrel for the Realist 620 is 57mm (2.25") in diameter not 38mm (1.25"). I think most slide projector lenses are of a standard diameter (?) and this may be in line with that standard.

I'm still rather hot over being deceived by the seller about the condition of the projector. I am considering returning it (spousal urging). I may post in Optics to see if there's someone willing to part with a compatible lens... then make a determination.

Either way, I feel I've interrupted Slick69's thread too many times, especially now that you're getting down to brass tacks! I'll make a project page if I get anywhere.

Can't wait for the photos. Carry on and good luck! ^_^
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