I'm in the proces of building a beamer, but i'm having some problems right now.

Specs beamer:
- 10.6" hd-ready LCD
- fresnels 220 & 330
- triplet 345
- FS mirror
- 400W Osram in lightbox with reflector and condensor

If I project on my screen i get a sharp and in focus view, but its far from bright.
Today is a very cloudy day and i have my room darkened, but i can hardly see an image on the projectionscreen.
Somehow it seems the light is not very good focussed trough the LCD.

pics (click for hi-res):



Overview (this is just a testcasing, as you can see i made a small calculation mistake for the height of the case )


Lightbox


Everything seems to be in line




Projection on the mirror, in focus (although placing of mirror is not optimal, a small amount of light is projected near it)




Weird thing: if I remove the mirror i dont get an (out of focus) round light, but a light square

Unfortunatly i dont have any pics of the projection itself, but trust me: you can hardly see the picture.
I made a 400W 15" beamer with a friend of mine, which was far, far more bright.

What am I doing wrong? I suppose the light square isnt good..

Are you sure all the distances are correct? From the pics alone (it may not be the case) but is appears that the distance from light to rear frensel is greater than that of the screen through the mirror and to the screen.

According to focal calc.... lcd to trip= 375mm where as light to rear frensel= ~220mm

Obviously there are going to be a lot of light leaks...not having a top and all, but that aside. Are you sure the frensels are the correct way round? Try moving the lamp set up back and forth to see if the level of brightness increases. similarly do the same with the pre-con...mine worked far better when it was very close to the bulb.

if you have a laser pointer check alignment...the mirror often can be slightly off, not putting as much light through the triplet as possible leading to diminshed light levels.

A few things to test there...if your still having probs psot back.

I think what windsor said about the light leaks is going to be a big loss of brightness. If you can at least cover the backend of the projector even with cardboard and tape or a towel just be careful dont burn the house down Try that and see if it helps

By the looks of these two pics, it seems the center of your mirror isn't in the center of the light path.

from the way it looks your 220mm "freynal" is either in the wrong spot, or way to far from the lamp. In my projector the 220 appears to be alot closer. By my eye ruler it appears to be 5 or 6 inches away from the lamp in my projector. I have a similiar setup to yours minus the fold, and I can watch my 10.6 with the lights on. ps... cool condensor and reflector mount.

pps. i would recheck all of your measurments. I do not know what kind of reflector or condensor you are using but at least the condensor appears to be too far away. You are probably going to want a more active cooling solution to your condensor if you move it closer tho.

Let's try some tests Neok,

1. Remove your precondenser and compare brightness without it.
2. See if you can move your light engine closer to the rear fresnel without the precon lens on and check brightness again.
3. Place a sheet of white paper over the rear part of the triplet with a drawn out circle of the size of the triplet itself and see how much light is missing dead center of it. This is a good way to check alighnment.

Thanks guys for all the tips&advice, I'm now fitting up all the open spaces, replace the mirror and modifying the case with a top.
I'll post as soon as all of this is done

I know other people had problems with lighting due to the folded design. if nothing else works great try taking out the mirror and make it straight shot.