Interest in 22" EFL w/ 5" Diameter Opaque PJ lens?

[Rox]

you forgot a very important point as well; throw.

If you have a small throw, better the focus will be.

[Mikey p]

Originally posted by superdaveumo
I have an 18" opaque projection lens on a 17" projector. The focus is great until you hit the corners (on a 17" LCD). They start to become blurry right around the Start button (windows) and the same blur in the other corners.

What is the focal length of the fresnels you are using in your setup?

[ukagr]

Thanx for your answers superdave, i had briefly tested my lens with 330 fresnel and transparency but was unsure if there were other factors i hadn't thought of. I will be sticking to 15" or smaller.

[Guy Grotke]

It's not impossible to make a 330 mm fl field fresnel work with an 18" fl lens, but it is certainly not optimal. The rear principal plane of the projection lens will be at least 18" from the LCD, and that would be with an infinite throw distance. With a 12 foot throw distance, it will be more like 20.6" (522 mm).

The purpose of the field fresnel is to send all the light rays passing through the LCD to the center of the projection lens. (That gets the most light through the lens.) So you can see that a 550 mm fl fresnel about 30 mm before the LCD will do just that. This is exactly why I recommended the 3dlens owner should make a 550 mm fl fresnel.

If you try to use a 330 mm fl fresnel, you have to play with the lamp-arc-to-condensor-fresnel distance to force the light into a diverging cone. Then the field fresnel can focus the arc image at the projection lens distance. (But fresnels don't work very well in this mode, since they are really a series of prisms instead of lenses.) If you fail to do this, the 330 fresnel will focus the arc image about 200 mm before the projection lens. By the time the light gets to the lens, it will have spread out all over the place. You will get a VERY dark image, like you had no field fresnel at all.

So you are much better off using a field fresnel that matches your projection lens fl:

300 mm fl lens with 330 mm fl fresnel
457 mm fl lens with 550 mm fl fresnel

[superdaveumo]

What is the focal length of the fresnels you are using in your setup?

My setup is this:

400W Ushio MH Bulb -> IR / UV Filter -> 220mm Fresnel -> 17" LCD -> 550mm fresnel -> FS Mirror -> 18" Opaque projection lens -> Screen

My throw is approx (haven't measured it yet) 95" and my screen size is about 78" diagonal.

[Quinn]

what brand lens are you using dave, thanks

[eatcaramels]

I contacted the guy at aaa today, and now he's asking $100, before tax and shipping for the 22" lens, and that's without the projector (so no front surface mirror), which he said he doesn't have any more.

I'm going to try searching around first before bending over for the 33% price increase.

I think we've established that the 18" comes from the Vulyte 2-4's, but does anyone know the model that the 22" E.F. lens comes from?

For price/performance on a 500mm field fresnell, is there anything (besides the 18" version) that competes with this lens?

Lastly, I'd like to start organizing projector parts separately by complexity/capability, quality, and cost. Anyone think it would be useful to have a ranked list of components like this, or does it only sound good to me because that's what I need?

[Mikey p]

Originally posted by eatcaramels
I contacted the guy at aaa today, and now he's asking $100, before tax and shipping for the 22" lens, and that's without the projector (so no front surface mirror), which he said he doesn't have any more.

I'm going to try searching around first before bending over for the 33% price increase.

I think we've established that the 18" comes from the Vulyte 2-4's, but does anyone know the model that the 22" E.F. lens comes from?

For price/performance on a 500mm field fresnell, is there anything (besides the 18" version) that competes with this lens?

Lastly, I'd like to start organizing projector parts separately by complexity/capability, quality, and cost. Anyone think it would be useful to have a ranked list of components like this, or does it only sound good to me because that's what I need?

100 dollars is a good deal for a 22 inch focal length lens. You don't see that focal length very often. The reason for the price increase is he knows there is a demand for the lens. That's only smart business in my opinion. Guys test show that this lens works excellent with a 15 inch LCD. The only other option I'm aware of is the Lumenlab pro lens which is double the price. Whether or not these 22 inch lenses work with a 17 inch LCD remains to be seen. I just received my lens from Ludek and will be testing it with a 17 inch LCD shortly. I should point out that these 22 inch lenses being sold by Ludek are not all Beseler lenses. The one I recieved is an American Optical Co. lens. Both lenses have a 22 inch focal length, are 4 and 5/8 ths inches in diameter, and the Beseler is 6 inches long and the American Optical is 7 inches long. As far as organizing projector parts, the "long throw" aspect of the diy projector is to new at this time. 3dlens just came out with the 550mm fresnel a couple of months ago, there was supposed to be a fix in the works for the DIYPC 135mm lens that hasn't happened yet, and the new 500mm Pro triplet lens and 650mm fresnel from Lumenlab haven't been released yet. I do know the Lumenlab lenses have been tested independently and work perfectly with a 17 inch LCD. If you are building a 15inch LCD projector, you have options. If you are building a 17 inch LCD projector and want guaranteed results, Lumenlab is the only option at this time. The Lumenlab lenses are supposed to be released next month.

[CCMCornell]

I think we've established that the 18" comes from the Vulyte 2-4's, but does anyone know the model that the 22" E.F. lens comes from?

I was the OP for this thread. I mentioned that it the 22" lens wasn't available on the Mark II, III, or IV. I should have explicitly stated that I think it's the original Beseler Opaque Vulyte model that has the 22" lens. I first came across this lens on ebay last spring when I first started reading about DIY PJ's and since then I've only seen 22" lenses with this model.

I'm planning on trying this lens with a 17" WS screen like the Westinghouse, but haven't purchased either yet because I keep spending my money on other stuff.

[superdaveumo]

Originally posted by Quinn
what brand lens are you using dave, thanks

Sorry for the delay. I am using the 18" Beseler. If you want to hear my opinion on this lens and a 17" screen look here:

My 17" Projector