Hello everyone. I've been lurking for a while now but I really need this question answered. I just bought a 17" LCD off of ebay and am about to start building. I have read many posts about using a the LL standard triplet and pro fresnels with a 17" and getting acceptable results, albeit with a very short throw distance. I am wondering if there is any source for an acceptable alternative to using the very expensive pro lens. My roommate and I are scraping together our minimal college student funds for this project and a $200 lens doesn't seem to fit. I have heard occasional instances of people using slide projector lenses, but I haven't a clue what to look for in terms of specs. Would any of these be suitable?

http://cgi.ebay.com/6-lens-for-Kodak-Carou...1QQcmdZViewItem

If an inexpensive source for new lenses is available, that would also be great. I really dig this forum and am anxious to get started on this project. Thanks a ton for any help!

EDIT: Just saw this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...s_promot_widget

welcome!

first off.. they aren't using the pro fresnels... they are using a 220/330mm fresnel combination. Those are the focal lengths... The actual size of the fresnels are 395mm square... they used to be available at diyprojectorcompany.com. I think you can still get them at 3dlens.com

I'm not too smart with the lense stuff, but you might try searching (google "site:www.lumenlab.com keywords") for an opaque projector lens... I think it was an 18" buhl lens? anyway just try opaque lens and it should pop up... then look for it on ebay.

It seems the only thing I'm good at is spreading my list of bookmarks... here's all the 17" LCDs using the LL standard ($30) lense that I've found...

http://www.lumenlab.com/forums/index.php?showtopic=12642
http://www.lumenlab.com/forums/index.php?s...ic=7278&hl=
http://www.lumenlab.com/forums/index.php?s...ic=7095&hl=
http://www.lumenlab.com/forums/index.php?showtopic=6701
http://www.lumenlab.com/forums/index.php?s...mp;#entry143241
http://www.lumenlab.com/forums/index.php?showtopic=8033
http://www.lumenlab.com/forums/index.php?showtopic=11498
http://www.lumenlab.com/forums/index.php?showtopic=10366

The Opaque 18" or 22" would work fine for you. They would increase your throw from 1:1 to about 1.6:1

But you would need the 600mm Pro fresnel and your box would need to be about 8" longer to acount for the increased focal length of the lens.

Many thanks for helping out. The fresnels shouldn't be any problem. Since LL doesn't have any in stock, I might substitute a 550mm and 220mm (maybe a 330 if i use a precondenser). As for the triplet, I have been scouting ebay all day and have come up with a few possible 18" ones, no 22" though. I assume they are pretty rare. Will I have any problems with an 18" vs a 22"? Does anybody know any good, cheap sources other than ebay? I am having a really tough time finding affordable ones (less than $100 including shipping). Would an overhead projector triplet work?

Anyone?

Ok I was looking into this to and wondering will a 18" triplet work with the pro fresnel from ll or do you need a 22" triplet.

The Pro fresnel (650mm) will work with an 18" and a 22" lens.

Does one work better than the other?

Dont take this the wrong way...

But you are spending more time looking for alternative lenses, which have a lot of variables, versus working a few hours of overtime and getting the pro lenses. With the pro you have a definable variable. with other lenses you may spend more time correcting the differences.

Just an observation.
Sometimes looking for a bargain doesnt always result in an overall savings...

That said, I hope you find a cool and cheaper solution...

SJ

Got an 18" opaque projector lens off of ebay that looks to be in good shape. It cost $90 shipped which was a little more than I was hoping for, but I'm glad that I have most of the parts I need gathered. I can't wait to get started. Thanks again for helping out everyone. You should be hearing more from me soon.