Not happy with the image my DIY Projector gives me

[nick[x1]]

Ok had this around a year now I belive, was o.k but then I decided its time to tweak it because the image wasnt very bright!

Lamp: 400w HQI Daylight with UV sheild
LCD: Benq FP567s? 15" 1024x768
Bottom Fresnel: 220mm LumenLab
Top Fresnel: 317mm Lumen Lab
Object Lens: Lumen Lab 320mm
Reflector: Some random 60mm dia seems to do the job
Condenser: belive its off diy projector comapany fl 75mm, dia 64mm

So thats the setup out the way

I have the projector hanging from the celing which means focusing this thing is a pain!

This is where problem one comes in, I had it setup before very well with it the size of my homemade screen (about 100" )

Now after tweaking with it all I cant get it back to the size of it and be in focus!
It ends up with the top totaly out of focus and the bottom perfect, then if i can get them perfectly focused it ends up / \ in that kind of shape

Hope that makes sense

Then another problem is brightness, I look at pictures of peoples 250w setups and they are brighter than my 400w setup although I have played with mine no end but still cant get it to work?

Also I am pretty sure that everything is centered up, but seeing as the center of the image isnt as bright as it should be maybe it isnt?

 

[germax]

When I was adjusting my projector solution for dark corners like this was to make sure that lamp side fresnel is on proper distance.

Moving it too close would make circle like this if I remember correctly.


For different focus on top and bottom you must have different distances from LCD to top and bottom of the lense.

In my case mirror was not on right angle but you probably don't have one so that leaves lense placement and LCD distances to the lense to be checked.

With 400W you should be killing.
I have 250W and it is great, and that without condenser.
Maybe you should try without it too...
I am not sure how much sense condenser makes on 15" setup.
I was under impression that condenser is needed for small LCDs.

Good luck!

 

[makey2]

you may have an issue that could be fixed by tilting the fromt fresnel a few degrees forward and back.
In my PJ when projecting at an angle I found that a small change in the angle of the front fresnel helps alot...

 

[nick[x1]]

Seem to have almost fixed the size problem, but still got the problem of the dark corners! and generally dark image

Without the condenser its even worse no matter how back or close the light is

Supose I should try moving it back with the condenser on -\

 

[germax]

Check your reflector as well.
It is supposed to make light on the wrong side of the bulb to reflect through the bulb back to fresnel.
If reflector does not reflect light through light arc maybe it is shaping
it and that is circle that you see.
Arc should be in the middle of the reflector sphere.

Something is limithing light. You should definitely see the difference as you move lamp in and out of focal point of the fresnel lense.


I hope this helps...

 

[nick[x1]]

Ok found a big problem which affects the light distribution over the image.

The rear fresnel is slightly bent,if you press it in using your hand the brightness increases alot!

I have treid leaving a book on it all night which helped a bit to flatten it back out but its still slightly bent

Buying a new one is not a option! im now a very poor student lol

 

[Miedosoracing]

I always squish mine between two pieces of glass. If not, it will warp, always, since it is plastic.

 

[nick[x1]]

I had some pretty bad fingerprints on the flat side of the rear fresnel and couldnt get them off, so decided that i would used methylated spirits. Now this got them off but has left some really bad marks which are worse than the finger prints (see attached)



I have about got the image the right size, and almost focused perfect (Dosent really show on photo) still working on the brightness issue

Anyone got any ideas on how to sort my rear fresnel as those marks are pretty bad and show up alot!

 

[nick[x1]]

helps to attach the image

 

[chevy1965usa]

Solvents (both polar and non polar) are bad for plastics, acrylics and rubbers. Use only light detergent and water....

 

[dj_holmes]

THIS IS A WARNING TO PEOPLE OUT THERE THESE PAST FEW DAY I HAVE BROKEN HUNDRESD OF POUNDS WORTH OF ELECTRICS!!!!! ITS THE SEASON!! SO IF U PRIZE SOMETHING PUT IT ASIDE FOR NEXT WEEK!!!!

 

[nick[x1]]

Ok well im going to order a new rear fresnel £20!!!! how crazy is that for some plastic

Meanwhile I plan on getting it all focused, even light distribution (perfect ) so when the new lens comes I will have a nice clear picture to watch

Now I got the light in the corners so it looks quite good (even with smuge marks all over it) but there is still a clear ring of darkness

The rear fresnel having a focal length of 220mm

Where abouts should the bulb sit? I have it so the focal point is in the center of the bulb which knowing me is wrong

This is without the condenser as well

 

[newby]

I noticed that the distance isn't always right. I had to move the LCD and back fresnel closer to the light and the brightness increased drasticaly and it also helped get the dark ring out around the screen.

G