135mm long-throw lense kit from diylabs

[Rox]

Originally posted by ancorp
I got an identical-looking lens with the same specs, seems like an excellent lens, worked well for my 17" flat crt to project it onto a 60 in screen.

were the corners 100% focused? anyway your throw on this test was quite short (2meters?) that means the lens_back--tv distance was long (51cm?) so it is not the way most of us will use it. I´m triyng to determine the FOV of 135mm lens but i can´t believe manufacturers don´t know it.

[jcbklyny]

You can get 100% focus corner to corner with the 135mm lens but you need one of the lumenlab 650mm fresnels. LL's wrong 790's work 100% corner to corner... but only up to 8 or so feet from the screen. When you move it back 10-15 feet you need the 650's.

[Rox]

i think this thifference on the throw can be fixed placing the lamp closer to the rear fresnell.

You mean 17" works right with 135 triplet? do you know the FOV JCB? your store has a pdf wit specs but i can´t download them.

[jcbklyny]

I emailed the company and am still waiting on a reply. The ones I have are the same as DIYlabs (diyprojectorcompany). I'm out right now so if your interested place your order with Alan.

[Rox]

i would order if i knew the FOV and it suits me.

[Rox]

JCB wrote: I emailed the company and am still waiting on a reply


no news? Why does nobody know the FOV of this lens? I think it is not interesting for you to make it known. All the tryes makin 17" with 135 triplet that i see are black cornered. I think that the FOV is just too thin for this kind of TFT.

Would like to hear coments about it.

[ancorp]

Originally posted by Rox


were the corners 100% focused? anyway your throw on this test was quite short (2meters?) that means the lens_back--tv distance was long (51cm?) so it is not the way most of us will use it. I´m triyng to determine the FOV of 135mm lens but i can´t believe manufacturers don´t know it.

Hi Rox,
Sorry for the really delayed reply (missed your post). Yes, the corners seemed 100% focused (I can actually do a re-test if it really matters) Remeber its a 17"CRT, thats like a 16" LCD. I also Tested the lens with a 20" TV, and it seemed to be right on the limits (got the corners, but the lens had to be almost dead center, no lens shifting). Yes, the throw was about 2 meters, same with the TV, abit more, with an image of about like 70-100 inches. With a proper enclosure and screen, a 20" tv with this lens will give a nice 60-100 inch picture (abit on the dark side, but with proper service mode adjustments, shouldnt be a problem)


Hope this helps,
Cheers,
Alex

[Rox]

thanks for your information but it is not very usefull my friend.


the throws you are using are too short. Thats why you need to place the lens so far from the image source (so 17" 16"real image enters the triplet even thought its small FOV.

The isues come when you use 17" tft real (17") and the trhow is 3m lets say. then the triplet is so close that the tft is outside of its FOV. So it does not work at the corners.

But the only thing i would like to know is the FOV value of this lens. Its getting hard to find it!!!!!! sellers seem not to share it with us, i wonder why

[ancorp]

Hey, Id like to help you, and test it at like 120", but the monitor simply doesnt have enough brightness...

[Squalish]

Rox, I direct you to this thread:
http://www.lumenlab.com/forums/index.php?showtopic=5230
His site has more info.

Basically, he got it to work by using the lamp at 220mm instead of the 330mm focal length. This made the effective focal length I think ~450mm, and combined with taking apart the triplet, got him reasonably sharp (I didn't see close enough for screendoor, but individual pixellation is visible) images.

I'm thinking that that's how I'm going to do it.