I've searched a lot of threads but most people it seems have not had good luck using a wide-angle camera lens on their projector. I tried to use a $50 lens before also with poor results.

I know there are many add-on short throw lenses made by projector companies but many of them are only made for biz projectors.

Is there a short throw lens that is more or less is"universal" for projectors?

Or a high quality wide angle lens that people have used that is successfully for projectors that cost under $1200 or so?

I'm looking into making a rear projection system with a front projector but I'm running out of ideas.

NEC makes a ultrashort throw lens projector but its only XGA, most of ultra short throw HD projectors are 10k +.

Chris

Hi Chris,

The Navitar ScreenStar series of lenses are the gold standard of short throw add-on lenses. The mini-screenstar 0.65x is around $900, and works on projectors with imagers .8" or less. This will give you a 50% bigger pic for the same throw distance. they are spoken highly of in the >$3K forum, but I haven't tried one myself.

I have a Sony VCL-HG0758, which is a 0.7x. It is the only one I've tried that will give acceptable corner focus. I tried quite a few mid-priced lenses, including the Raynox HD6600, as well as the Olympus WCON-07 and WCON-08, and could not get acceptable corner focus. These were all tested with a Mits HD1000, which has a .65" imager.

Even this Sony ( which has a huge ( close to 80mm ) front element, is tricky to set-up. You have to build an adjustable mount for it that will allow you to adjust the height and pitch of of the lens, so you can centre the beam from the primary projector lens.

As far as rear projection, .65x doesn't really buy you too much. For most of the LCD's, you can get 100" for 10 feet, so, a .65x would shorten that to 6.5 feet ... still a lot of throw needed for a rear projection system.

A better solution is mirrors. A single mirror will allow you to reduce your throw by nearly 50%. Multiple mirrors are more difficult to setup, but can reduce the throw even further. I've had good luck with a single mirror system just using an ordinary mirror. For multiple mirrors, the last mirror in the bounce should be a first surface mirror, or you'll get ghosting. The cheapest way to get first surface mirrors is from junked RPTV's.

If you can live with 480p, the Toshiba ET-20 'all-in-one' projector / DVD player can throw a 100" pic from less than 4 feet.

The Mits WD-2000 has an ultra-short throw lens designed for rear projection available as an option, but you'll be pushing close to 7K for the projector and lens.

Hope this helps,

Jonathan

Maybe a higher quality wide angel lens is the key. The guy who first posted success a long while back with a wide angle lens was using a $150 canon lens, I believe.

You are looking to do the same thing I was (and possibly still am). I will also be using mirrors too.

Thanks for the great posts! I'll have to do some experimenting. So I can buy just a regular mirror and it will provide good results? Does the mirror have to be of certain dimensions? This would be used in a single mirror project.

Thanks

A first surface mirror will work optimally, but I've had good results with a regular mirror too. It just needs to be clean though. The mirror just needs to be able to hold the image you should onto it. The dimensions don't matter too much as long as long as it can hold the entire width and height of the image you're reflecting off of it. Still, 16:9 or close to it would be optimal.

I was going to use a 2 or 3 mirror setup possibly in combination with a short throw lens so I could keep the depth of the set under 3'. Hopefully less than 2.5', too. It gets a bit complicated with more mirrors though.

How much depth are you planning on the set being and what is your screen width goal? See, I was going to build mine like a large RPTV with a black enclosure. I'm not sure if that's how you're planning on doing yours.

Yeah I was going to build mine like a large RPTV as well, but I could deal with even something with 6ft depth. Obviously, the less the depth the better.

I'm actually on my way over to Jo-anns fabrics to see if I can find a cheap sub. for rear projection material.

Chris

Man, with 6' of depth it should be EASY (well, in comparison to what I'm trying to do anyway) even without a short throw lens when you get a mirror. I could probably do over 10' wide no problem if i had only 5' of depth. The problem is, my room is only about 16' deep would then become 11' deep. With a 3' deep couch that's 8' left between the couch and screen and about 10' from my eyes to the screen and I've been wanting at least a 10.5' wide screen.

Actually I'm willing to go at deep as 4', BUT, I'm trying to make something I can sell online and I'm even working on an idea for a custom black beaded rear projection screen.

What is the depth of the room where you'll be doing this project?

The main reason why I have been considering not going with rear projection though was because I have really been wanting a LARGER image than my current 8' wide screen (about 110" diagonal). I want 10.5' wide at least.

As for rear projection material that is good and cheap I recommend Dark Gray PVC rear screen materiall. Dazian has it and it cost me under $100 for an 87"x 108" sheet. It's 1.8 gain. I actually took some screenshot in ambient light with my 4805 that I may post later. The picture is AWESOME in ambient light. It's much better than a regular screen in ambient lgiht and even better than my SPVC.

BTW, if you need a short throw projector look into the Sharp DT-500 if you want DLP. It has a pretty impressive short throw. It also has an iris you can adjust for higher contrast or higher brightness, depending on the situation. I got mine for about $700. It's about on par or better than the HC3000U. How cheap you get one depends on where you get it.

If you want super short throw the Toshiba ET20U can throw 100" from 3.9' away. It's about $900 and it's only 480p. Still should look really good though. It certainly simplifies things. :) 480 can still look damn impressive, but I certainly wish it was at least 720p considering the price.

Our room is 20 ft long so I have some room to play with for rear projection. I'll def. check out the Dark Gray PVC material. For under $100 thats a great deal. One of the materials that looked neat that I've read about other people using is white spandex. I'm worried it may be too texturized but I'll try a sample size this weekend and see how it turns out.

Yeah I was looking at some of those projectors you mentioned, another one even though its a generation old is the DT-400 which has an even shorter throw then the 500.

Yeah if you get a chance I'd love to see how your 4805 preformed in ambient light.

Good luck with your project to create a really thin rear setup. I'll be very interested to know how it turns out. I'll also let you know how mine works out when all is said and done. Thanks again.

Chris

If you want good ambient light go dark gray. Using white makes it almost pointless to go with rear projection instead of front projection. It basically just slightly improves amibent light, but it does improve ansi contrast in the dark.