Extremely Short Throw Projector Setup

[niedzielski]

I am trying to put together a very short throw rear projector system for an arcade cocktail cabinet style project. The constraints of the cabinet are quite severe, the projector and throw distance must total to around four feet or less, and as little a projection angle as possible, preferably dead-on. Overall, the other main project constraint is that the lens and projector should cost less than $3000 in total.

 

I checked out NEC's WT610, it has an awesome wide angle projection, 40" image at a 2.5" throw. Unfortunately, the projector has a 55 degree projection angle, so even at 2.5", it's 14" from one end of the canvas. I've since been looking at other projectors, but without much success, can anyone recommend any other extremely short throw projectors?

 

I've also tried looking for a more traditional short throw projector, that is a projector with a throw ~3'. To this, it was my intention to add a high end wide angle lens. I've seen the FUJINON COPY LENS, 240MM FL referenced at http://www.lumenlab.com/forums/index.php?showtopic=26, but this seems to be more of a camera lens (it's 3.22" wide). I've also seen this "Wide Angle 8mm Projector Lens f/1.6" recommended elsewhere. Does anyone have any advice regarding these lens or can recommend another lens that provides extreme short throw?

[Jivemaster]

Stephen, this is a UK theatre and events forum, a few members will have stateside wisdom, but only a few, however;

 

Look at the possibility of folding the beam with a mirror or two.

 

Look at suplimentary afocal wide angle adaptors ( http://www.photographic.co.nz/dtv/content/...les/Default.htm ) is a guide. Camera and projector afocal lenses function identically! But they have to fit the projector!

 

The Fujinon lens you suggest will be for a very flat field at a limited range of magnifications from a large size original, it is not an Afocal adaptor, the WA projector lens is specific to a range of 8mm movie projectors and will be useless for you.

 

 

Keep an eye on http://www.blue-room.org.uk/index.php?showtopic=19485 where a similar topic is getting some ideas.

[niedzielski]

Thanks for the help, Roger. I didn't quite understand your explanation of the Fuginon lens, but I decided to revisit the WT610 and use a mirror as you suggested. I've also decided on a screen size, 3' x 4' or 60" diagonally. Using the installation guide, I was able to draw up the following side view:

 

http://www.dreamtangle.com/wt610_setup_profile.gif

 

So, above you may picture the drawing being rotated left 90 degrees so that contraption stands like a table. My greatest concern with this setup is the scale and proportion of the beam of projection, as I am uncertain how precise the diagram I used from the installation guide is. I've contacted NEC, and await these hopefully forthcoming technical details. Other than that, I'd appreciate anyone pointing out problems with this setup, or a good place to buy mirrors.

[mackerr]

According to the page you linked to, this projector was discontinued in Oct, '06.

 

Mac

[niedzielski]

That's an excellent point, Mac, something I hadn't noticed. This may affect the level of support I receive from NEC, but I don't think I will have trouble finding one to buy.

[Jivemaster]

And please check that the projector will accommodate the inversions that the mirror will create. Your diag looks like inverting the image.

[Shez]

That projector will do front/rear and normal/inverted projection so should accommodate your image whichever way up you want it. Positioning is absolutely critical and getting a square image is not easy even in a conventional installation. It uses curved mirrors so you won't get perfect straight edges anyway but it does have very comprehensive key-stoning. Position it so the image is slightly larger than your projection surface so you've got a little leeway for tweaks. I know it's happy to sit the right way up or inverted but you might want to check whether it's OK to be on it's back - lamp orientation & cooling system may not appreciate this.

[niedzielski]

Some good points brought up. The projector will be receiving a video feed from a computer application, which can handle inversion in software, if needed. Cooling is a bit of a growing concern for me, I'm hoping it may be handled by some small, quiet computer fans, I'll have to contact NEC about that. Thanks for the help, guys.

 

With regards to the above setup, it's not to scale. I didn't realize it before, but in the drawing you may see that the 10.16" gap is greater than the 10.3" gap. I checked the numbers and unfortunately they're right, so I must conclude the drawings in the manual are not to scale. NEC called me back this morning regarding the projection beam measurements, unfortunately, they said if I really want the information it'll take two to four weeks because they'd have to get it from the guys in Japan. Thus, I'm hoping I will be able to find a WT610 in the area and make some approximations on the beam.