Hi all. This is my first post, so be gentle. I'm looking to project a 85" wide image from about 14 feet away. My question is what kind of lens would I need for this. I have tried the calculator, and at 14 feet the screen will be about double of what I need. I have found a 22" lens on the net, but i'm not sure if that will do. Also is there anyway to adjust the projected image size, without moving the projector closer? I will be using a 15" lcd. Any help is appreciated.

One more thing, I been looking at a ton of lenses and am getting confuses. For example this lens here is 7.0" (177.8MM) F:2.5. Now I figure that 177mm is the focal length(so I would need a 177mm frsnel(just an example). Now does "F" stands for the ratio(same as the s15 lens on this site is 1:1)? So would this lens be 2.5:1? I know this might sound retarded, but im just so confused right now.

to get 85" diag image from 14 ft throw you will need a 25" FL lens.. good luck with that 22" lens will give you ~99" diag. only way to adjust image size other than modulating throw distance is changing the size of the image on the LCD. I.e. using a 22" lens you could scale the image on your LCD to 12.8" diag and get the 85" screen from 14 ft.

also, you need the collimating fresnel to have a focal length longer than that of the triplet

Ok, I think I might be back on track. One more thing tho. Does the FL of the fresnel need to be longer or shorter then the FL of the lens? For example the 22" lens is about 559mm. So do I need a 550mm fresnel or something longer?

Edit: I just picked up a 24" lens for $50(I think that was a good deal). Anyway, so now I guess I need a 650mm fresnel. Is this correct?

FL of the fresnel needs to be longer. 24" is almost 610mm. The 650mm LL fresnel really has a FL of 600-605mm so it may or may not provide a good picture. I'm pretty sure you can find longer FL fresnels though.. I seem to remember someone on the board using a 700+mm fressy.

Never seen a 24" . Pics or links please

Same here, info please.... I need to throw 95" at 16'.

Well I got super lucky on ebay. The guy closed the listing early for me. Here is the LINK It's a Beseler lens. Hopefully I should get my 85-90" from 14 feet(atleast the calc says so)

Now I just need a 700mm fresnel...Anyone know where to get one?

I'm having a problem finding the right frensel, the longest I can find is 610mm. What do you guys think? Does anyone have a 650mm pro frensel for sale?

You can get the 650mm fresnel to do the trick, basically you just fool the secondary optics by placing hte lamp closer to the collimator fresnel.

The result is that the collimator fresnel on't QUITE be able to collimate the incoming light, it will still be diverging somewhat. Then when it hits the collector fresnel, it will re-focus, but proportionally further away.

What do you think about using a 610mm? Since I'm having a very hard time finding a 650mm.

the FL of the 650 is 600-610mm

I just ordered the 610mm, as I didn't have much choice. Hope this works with that 24" lens..