Hi guys, im from Serbia and English is not my stronger side,so i would like to ask you for the simpliest answers.

Today i recieve a FL from Lumenlab(thanx) and i have some questions for whitch i didn`t find the answer, or just couldn`t understand.Im building my first projector and in my country that was not cheep thing to do.Just to say that our montly pay is about 250 USD, so dont want to screw some things up.

1.When i mesure the focal length from second fresnel to triplet,is it from lens to the enter of the triplet or from lens to the midle of the triplet or something else?

2.For the keystoning,do i have to mount fresnel in the midle so i can move the top and the botom side, or just mount to the top and live the botom side of the fresnel to swing?

3.About lexan LX10, here in my country nobody was ever hear about that lexan so if anyone have some link where i could by this thin(i hope i can afford it).

4.And last queston(for now) is how can i mesure the focal lenght of triplet,coz im using a triplet from some old school projector.It`s quite big, it`s 16cm long and wide is about 12.Hope this can match the 320mm fresnel.
Here`s one picture of it. http://static.elitesecurity.org/uploads/1/...et%20socivo.jpg


Im sorry for my wrighting, i never learn English in school, and just hope you understand the questions.

I whish you all the best.

Your English seems quite good! I believe it's to the "EFL" of the triplet which usually is assumed to be to the center of the triplet or halfway from front-to-back or - as you said - the "middle".I believe it may be done either way.

Lexan XL-10 is available on the internet. You'll probably have to do a little research to get the best price for where you live.

I can't answer your other question but someone else certainly will and perhaps will expand on the answers I have given you.

Best of luck!

Hello StexMan, Im new to all of this myself but ill try to help out.

1. Im thinking it is to the center of the triplet.
2. I used a dowel rod hung from the top so that the lens can swing @ the bottem to get keystoning
3. I used tempered glass instead -- Tower hobbies has clear lx-10 sheet for sale
4. The triplet I used was to from a old school pj there is a focal calculator in the Calibration and Tools section of the fourms that you can use to get the right distance of all lens's

also a link with alot of good info is the wiki http://www.lumenlab.com/protectedwiki/Welcome

Tnx guys for the answers.I have one more what is the best color temperature for lamp.I find here some diferent opinions so now i cant decide.I found in our stor two diferent lamps.One have a colour temp. of 3700K and the other 4700K.Both are made by OSRAM and have 400W,31000 Lumens.I think that other one would be bether.
Tnx again for info.

For color temp you generially want it to be higher. I would buy the 4700K bulb.

Hi again, i have few more questions for you guys.
I realy cant decide between two designs, Haas style or vertical.So i need to know what size had to be FS mirror for vertical design.
Also about reflector,could something like this can be used?

or maybe that tempered glass in front of the reflector?

Tnx.

[edit]Now the pic is working[/edit]

Do you see it now?

Yup, working now.

Um, it would probably make the image a little brighter, but a smooth spherical reflector is the way to go.

I can't tell, but there's some kind of piece of glass in the pic as well. I wonder if it's a hot mirror...? That piece of glass may come in handy if it is a hot mirror.

A horizontal design (Haas) generally requires much less fiddling with to get optimum results and for a simpler, more forgiving build, it would be the way to go. The mirror will cause a little light loss (less brightness) and can require a lot of delicate adjustment to get a perfect picture.

@ Hirudin -So i could use that like a reflector untill i find a sferical one?And i think that is a hot mirror, it looks a bit greenish and dimension are about 4cm x 20cm (1.57x7.87 inch) and it`s 4-5mm thick.Do you think that would be enough size for use like a IR filter?Do you want to say that hot mirror dont need to cover a whole aria of the Fresnels lens?



@ Durachko - you got me there, i realy like the haas design coz it actualy looks like projector.All i needed is one vote for the Haas, and with your post Haas wins in favor 51-49% votes.

I can`t wait to start making one, but i still havent found bulb.

And tnx again guys, i realy appreciate your effort to help me.

@ Hirudin -So i could use that like a reflector untill i find a sferical one?And i think that is a hot mirror, it looks a bit greenish and dimension are about 4cm x 20cm (1.57x7.87 inch) and it`s 4-5mm thick.Do you think that would be enough size for use like a IR filter?Do you want to say that hot mirror dont need to cover a whole aria of the Fresnels lens?

thanks.

Sorry about not replying sooner, I have only used one reflector, and I don't think I've ever even seen a hot mirror...

Um, I suppose you could use that reflector... I'm not really sure. Personally I'd try with and without it if possible.

I would imagine just so long as all the light hitting the panel has to go through the hot mirror that would mean it's big enough. If some of the light hitting the panel doesn't go through the mirror you'll probably have a visable line on your projection because of the edge of the mirror...

4cm is pretty small...

Ok, thanks.