I am posting this diagram so that everyone can comment on and correct if necessary my understanding of how to use the new Pro Lens Kit.

My thanks to Rorshach & Brain for allowing me to modify and re-post this diagram in the LumenLab forum.

So what do you think, is my design correct and will this work? Can you think of a more simple or better way? I appreciate all comments and critiques you choose to make.

I hope that this diagram will help others to understand how the new Pro Lens Kit works.

Thanks.

Star

I forgot to tell you that because all the lenses are already in mm
I found it easier to continue the measurements in mm for the length of the box
but because I can think of sizes better in inches I choose to use inches for the height & width of the box. Sorry for the confusion.

Star

Thanks for the picture. I am waiting on the new lenses and I am going to make a box the same way. Not cutting the fresnels so that I can upgrade to a bigger lcd later. Your measurements will help when I get to actually building this beast.

Corbett

Remember that the 572mm is from the back of the pro lens to the lcd not the fresnel.

Mark,

Thanks for the correction. Below is the corrected diagram (width from LCD to Fresnel is 20mm so 572 - 20 = 552 from fresnel to Triplet lens.) Thanks for saving me from my own mistake.

Can someone please update this diagram with the corrected distances now that the problem with uneven light with norpro/prolenskit combination have been solved..


The Edge

Actually it hasn't been totally solved. I can say that for best performance use both lenses behind the panel.

If both (fresnel) lenses are behind the panel, how is keystoning corrected? Does this imply that, ideally, the 790mm fresnel should have a shorter fl for the larger lcd panels?

Was the use of split fresnels driven by the ease of keystone correction? I was reading on another forum that the picture will be brightest and sharpest if both fresnels are in front of the LCD panel (on the light source side).

I thought I read somewhere here that the original recommendation was to have both fresnels on the bulb side, also?

Thanks.. Ed

It was the original recommendation. Chick, the focal length is indeed too long but not in so much as the specifications were wrong, but rather the fields lenses appear to be about 50mm longer in focal length than specified. I'm trying to work this out with the manufacturer and will get back to all regarding the situation.

huh??
Am I to understand this is a change in the setup to move the fresnells
back to the same side?



R

Edit- NM,,Brain clarified above.

I'm lost also. ?? ??


peace

I'm sure there will be a posting clearing everything up. Just give em a little time to get it worked out - we havent been left in the dark for very long in the past don't see it happening now.

Whoa, so the original plan of Frensal --> Lcd --> frensal is no good? should i hold off on my building for a bit?

Go ahead and build away. Performance will be better with both lenses behind the LCD.

No keystone though.
Is that right?
Do you put the lenses back to back or seperate them by some distance?

Thanks,

R

Back to back. China acknowledges they made a mistake on the fields. Replacements on the way.

Refunds and exchanges?


peace

I don't get it. I thought the idea behind the second fresnal is to focus the image into a point.
So why would we want to focus the light from the bulb and not the image from the lighted LCD? This just seems to defeat the purpose to me.

?? ??

Of course we will replace the defective lenses, please allow us time to work out the problems. The froward fresnel is a light collecting lens. Whether it is in front of or behind the panel it still functions as a collector lens.

Sorry, hope you don't think I'm whining or being impatient, one thing that I am gifted with is patience.
Just trying to get it right.


peace

Thanks

I am now fairly confused. I am preparing to build my first projector, and do not know which sequence of fresnels I should now use. I would like the greatest quality and brightness. Should it be fresnel, fresnel, LCD, or fresnel, LCD, fresnel? If it is the first, will I lose some of the image from the LCD??

Also, what is the advantage of the Pro Lens kit. If I am going to use a 15" LCD, should I get the regular kit, or the pro lens kit?

The best arrangement is F/L/F...you get keystone and even lighting. The pro lens is going to give you the long throw, which can be very important. Being a huge lens it is far superior in its transmittance capabilities, and can also zoom.

And It looks cool too!!!

is the pro for 17" or 19"?
Also shouldn't pixels be important? I only see people talk about response time and ratio.

The pro can be used for any size panel up to (we believe) 21", perhaps even bigger.

hi brain, i have been enjoying my projector for almost 6 months now and never been back to this forum since. i am wondering though, have you made a new guide for the new projector using pro lenses?

Actually no, coming in revision 4. Trying to get all the bugs worked out first

HI,

I've been lurking in the forums for awhile now....soaking in what I can. Let me make sure I'm clear on a couple of things here, if I may.

I'm making a 15" basic vertical design but I'll need a pretty long throw...about 15' to 17' and I won't always be able to get the room completely dark.

First question: Do I absolutely have to have the pro lens kit? Or would it simply mean better picture quality if I go that route?

Second question: Brain, are you saying that once the new, correctly fabricated fresnels are in, that we should leave them together? If I choose to do my keystone correction with my mirror at the top, should I leave them together no matter what?

Thanks,
The new guy

If you want your projector 15' back you'd have to use the pro lens.

You do not need to leave the correct lenses together. Your light distribution will be better if they are separated.

Correct me if I'm wrong (Anybody....) but you can't use the mirror on top for keystoning if your doing the simple verticle design. Any movement of the mirror off axis simply moves the image away from the desired lens envelope. Keystoning needs to be done on the fresnel, or an external mirror if used.

Just wanted to mention it...

just read about the defective fresnels how do i find out if the ones i have are defective?

I believe that all of the field fresnels with the pro lens kit were wrong. If you have the pro lens you should have recieved an email from them.

so using the defectiive fresnels all the measurements are the same for the whole projector, the only difference is to put both fresnels on the lamp side of the lcd sandwiched together, then when the replacement frensels turn up install the new ones on either side of the lcd.

is the correct ?

is there a big diffence in image quality using the defective fresnels ?

I asked about this when I previously came across a comment on the forum about the pro lens kit fresnels being manufactured incorrectly. Still no reply to that, and what's more, I've had the pro lens kit for quite some time now and I have not received an email from "them", whoever "they" may be. As it is, I have purposely delayed building my 17" LCD projector for another reason but it would appear that I am about to experience yet another extension. May I ask what are the official arrangements that have been decided upon to take care of this situation ?

Read Page 31 of the Zoom Lens thread. From there, Brainchild explains the problem wit the Pro Lens' field fresnel, and explains what will be done. Read the Daily News for updates as they come.

I've recently moved.

Brain, I'll be more than willing to pay for the shipping, but please make sure you get my new address before shipping. Thanks!

Edit:
Been reading the forums, somebody needs to organize this stuff in the guide!
Just got my hands on a Dell 1702FP and I am looking at using the Pro lens kit.
Did some 3D drawings and wonder about the focal lengths of the Field Frensel
and the Lens. The Pro Lens has a FL of 450mm-500mm but the Field Frensel
has a FL of 790mm. Please see attached images. There is probably an answer
somewhere in the forums?

I actually have the same question. I am not quite sure on placement of the pro lens withthe pro fresnels... especially with "zoom feature" and the correct setup of that. It would be great if the person answering that could include that in the reply or references to elsewhere. Nice drawing though.

You've pretty much got it right except the field fresnel has been changed to 650mm. What is confusing you I believe is the fact that the field fresnels focal point is beyond the triplet. This is done purposefully because the triplet focuses on the panel not the fresnel. The sole purpose of the fresnel is to collect as much light as possible and direct it to the triplet. Your drawing clearly illustrates this point as the field fresnel fills the entire triplet with light as it was intended.

I hope this clears things up for you, I wasn't really sure of your question. Nice drawing, by the way. [edit] but you will need to change your distances.

Are you volunteering to organize this stuff?

Worldprojector; I do know that the mean placement of the pro lens is 572mm from the panel + or - for the zoom or focus (which one I'm not sure).

Great explanatory diagram "nisus".

One question, "Will a lens of 100-200mm shorten the FL distance and in the process shorten the box." Reason I ask is, I have a few outside chances of getting hold of a few huge lenses from a giant 3 lens monster made by Sony. It is large enough to gut and use for the 15" project that I am collecting materials for. These buggers are big. I have added a diagram of the idea as below. Comments on the viability are most welcome.

Holdfast

Those 3 gun crt projectors were designed to have the lens within 0.5" of the crt so unless the LCD cab be that close and totally in view they won't work unless you're using a <5" lcd

Thanks pagercam,
I was outbid on the three holers, but I did get a Plus UP-880 Projector in full working order and a Plus DP-30 (Direct Projector) with a massive lens.

Holdfast

Removed to a more appropriate location
Holdfast

Removed to more appropriate location

Holdfast

Brain
Do you mean groved side to groved side as the guide would indicate? I've got my Pro lens projector together (folded), checked the measurements, made the 6" polished aluminium cake mold movable while the unit is on (moving had no effect) and the picture is a little dull with the corners being darker. Should I trim back the reflector? move the bulb? shuffle the fresnels? The 220 is at the back(bulb side) with groves facing forward, the 770/990 fresnel is against the first fresnel with the groves facing backward? I'm using a SGI 1600 panel(cruser) Help please!

Barry

I'm going to use a 15" monitor and only throw it about 10-11'. Because of this I was planning on using the regular fresnals. With the regular fresnals will I get a better quality image by placing them togeter or placing them f/l/f?

anybody?