Hi folks! This is my first post as I am new to the forum. My name is Peter.
I have just assembled my projector and got to do some test runs. It's a folded design with a fresnel from an OH and therefore also unsplit. Previously (when not using lcd but OH-sheets) I focused on a bright white picture.
Now I discover that my picture has bright areas over and under mid-point. I can't seem to make them go away no matter what. The picture is over all too bright except for the area between the to areas. If I play around with the lcd's contrast and brightness I can somewhat lessen the effect but the picture is still strongly affected by this problem.
If it isn't the alignment of the lamp (it's at least very close to the perfect spot), I suspect that it has to do with the panel itself and its polarization filter? Anyhow, I just don't know for sure what is causing this and would be be very pleased if someone would help me!
I have just assembled my projector and got to do some test runs. It's a folded design with a fresnel from an OH and therefore also unsplit. Previously (when not using lcd but OH-sheets) I focused on a bright white picture.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Now I discover that my picture has bright areas over and under mid-point. I can't seem to make them go away no matter what. The picture is over all too bright except for the area between the to areas. If I play around with the lcd's contrast and brightness I can somewhat lessen the effect but the picture is still strongly affected by this problem.
If it isn't the alignment of the lamp (it's at least very close to the perfect spot), I suspect that it has to do with the panel itself and its polarization filter? Anyhow, I just don't know for sure what is causing this and would be be very pleased if someone would help me!
Okey. I tried moving the fresnel up and down, unfortunately I can't bring it closer or more far away at the moment (because of design). Moving it up or down just seemed to do the same thing as to move the lamp a bit.
I also should mention that the upper brighter area look kind of inverted during movies. If there is a dark background and with something white-coloured near the top, everything kind of inverts. All darks turn bright and the white matter turn dark. This is not true on the bottom area of the screen. The effect looks very much like my laptop screen if you get really close ( like 4 inches), the top bar changes colour and the bottom turn brighter.
It might not be related because on the projector it only seems to affect darker lit scenes and on my laptop-screen this effect can be seen anytime..
Do you suggest my to change my fresnel or something else?
I also should mention that the upper brighter area look kind of inverted during movies. If there is a dark background and with something white-coloured near the top, everything kind of inverts. All darks turn bright and the white matter turn dark. This is not true on the bottom area of the screen. The effect looks very much like my laptop screen if you get really close ( like 4 inches), the top bar changes colour and the bottom turn brighter.
It might not be related because on the projector it only seems to affect darker lit scenes and on my laptop-screen this effect can be seen anytime..
Do you suggest my to change my fresnel or something else?
I just realized what I think it is..
Watching an all black picture on my desktops monitor gives me a pretty black picture whilst watching the same on my laptop will give me the exact same experience as mention in my first post. Cheap tn panel, as cheap as the one in my projector I realize..
Changing concept to a split fresnel design will make this go away I think.
The weirdest thing is that I can't seem to find anyone else who asked about this problem before.
Watching an all black picture on my desktops monitor gives me a pretty black picture whilst watching the same on my laptop will give me the exact same experience as mention in my first post. Cheap tn panel, as cheap as the one in my projector I realize..
Changing concept to a split fresnel design will make this go away I think.
The weirdest thing is that I can't seem to find anyone else who asked about this problem before.
I might not be the most recent screen. Bought it from diy-beamer.com. It's a Toshiba 12.1inch. Said to have 600:1 in contrast. In any case, I did split my fresnel and placed the one in front of the panel instead. Worked like a charm. Now I've got a slightly brighter upper half, but this time I suspect the lamp position.
Another issue I have wondered about is the controller board (MST9E19A, came as a kit). It overscans the picture a bit. Probably because someone thought it was a good idea to make 1280x720p its native resolution? The screen should do 1280x768 according to the webpage. To be honest, I haven't played around with resolution settings but it would be nice to have 1:1 mapping. At the moment I think that 720 lines is zoomed in into fullscreen?
At the moment I have a totally usable projector at least!
Another issue I have wondered about is the controller board (MST9E19A, came as a kit). It overscans the picture a bit. Probably because someone thought it was a good idea to make 1280x720p its native resolution? The screen should do 1280x768 according to the webpage. To be honest, I haven't played around with resolution settings but it would be nice to have 1:1 mapping. At the moment I think that 720 lines is zoomed in into fullscreen?
At the moment I have a totally usable projector at least!
Uneven light? Do the paper bond test to see if the light cone is centered to the projection lens.
The controller for LCD TV like yours has overscan setting. But its a hidden setting only the supplier/manufacturer knows all about it. Default overscan for LCD TV is normally 30% vertical and 30%horizontal. And this is also programable when a software is loaded to the controller.
Overscan is different from digital zoom. Overscan improves image quality but zoom degrades image quality.
The controller for LCD TV like yours has overscan setting. But its a hidden setting only the supplier/manufacturer knows all about it. Default overscan for LCD TV is normally 30% vertical and 30%horizontal. And this is also programable when a software is loaded to the controller.
Overscan is different from digital zoom. Overscan improves image quality but zoom degrades image quality.
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