I have a 15" screen I'm going to use and I would like a little extra throw distance but was hoping that given the difficulties getting the pro fresnels that the pro throw lens might work with the standard 15" fresnels, at least enough to boost the throw a bit. Or would the shorter fresnel FL negate most of the advantage of the larger FL of the pro throw lens (ie the front fresnel light cone is too short)?

I've seen a number of posts about using a 15" with the pro lens kit and a few on using the standard kit with a 17" panel, but I haven't seen any on mixing the 15" fresnels with the pro throw lens (apologies if it is there and I missed it).

Thanks for any input and Happy New Year!

Chris

Won't work you need the back focus and the field fresnel to have similar focal lengths and the 15" fresnels are 330mm and the Pro Lens needs something like 790.

I thought the throw lens is focused on the panel so wouldn't it be possible to move the field fresnel forward so the light cone from the field fresnel hits the throw lens at the right point? The rear fresnel is focused on the bulb so that the light from the bulb comes out of the rear fresnel perpendicular to the panel. I suppose if there is any spreading of the light between the rear and front fresnel then moving the field fresnel will be more than problematic, and make keystone correction pretty much impossible. To squeeze a few more mm out of the field fresnel wouldn't it be possible to have the field fres moved back and allow the image to be inverted on the throw lens (rotating the panel to acount for that of course).

Now I'm confusing myself so I made a crude picture to help explain myself (forgive the poor graphic abilities).

Seems like this same concept was used to make the bad pro fresnels useable until the good ones come in (ie moving the field fresnel back between the rear fresnel and the lcd panel). Or maybe I'm just a complete ignoramous and don't understand this stuff at all instead of the little bit I thought I did...huh?

The image upload didn't work apparently. Trying again...

i suppose what you are trying to do is use the regular lens kit with a box designed for the pro kit and not having to hack up the box to make it smaller?

I'm not an expert on this by no means, but I can say with confidence those drawings won't work. I can just imagine how messed up the picture would look.

I'm probably just grasping at straws here but the idea is more for having the longer throw of the pro throw lens (same size image from a PJ set farther back than is possible with the standard throw lens) but use the standard 15" fresnels. I have a 15" panel and don't necessarily want or need the 17" or larger panel the pro lenses are intended for. I also don't see an end in sight to the problems with the pro fresnels (no offense to Brain) so getting those and cutting them down to size isn't really an option. No need to hack up a box I haven't built yet...

I would hope at least the first one (15" standard) would work as that is the basic LL design!

I hope you know I was referring to drawings #2 and #3.