I've got an optoma EP910 projector that I've pretty much been happy with. I have significant ambient light at times, and this projector has worked great for my needs. I am sending this unit a native 1400x1050 resolution through a Calibre Vantage HD scaler. My problem is when trying to calibrate the unit, the contrast (or brightness) at a midway point does not "fade" properly. On a grayscale from white to black, about halfway through gray, it starts to "macroblock", and then continue through the spectrum. At any point in video when it hits this grayscale point it basically distorts through this grayscale point. I'm not sure if there is there is a term for this, but how can this be resolved?

I have tried the VGA, and the DVI inputs and the results are the same.

I have tried throught the vantage HD, and then tried a PC, and the same thing.

Any help would be greatly appreciated.

Try changing your gamma settings. If there are modes that say cinema/film or something like that. PC level gamma's tend to crush shadow and highlight detail.

Changing the gamma did not change the irregularity....It just shifts the distortion point.

Anyone else with any ideas? It almost looks as thought the contrast issue maybe getting slightly worse. Not sure if I just notice it more now or what. I may contact optoma, and see if this is a defect.

Unfortunately, business projectors like that are not known to have tuned grayscales for home theater use. If you can get into the service menu (no idea how on this particular projector) you may have more fine grained control over gamma or individual color curves.

I have adjusted the gamma (brightness, contrast, etc...), and it still has the pixelation issues. Changing the settings basically just shifts the distortion point around. It is really noticeable with sky schenes, or where there is a gradual transition in color that happens to cross the faulty contrast band.

I have just yet to hear of this happening to anyone else.

One other thing, you can get rid of the anomoly by dropping the brightness and contrast ratio extremely low. Then there is no issues, but the contrast and brightness are horrible. I hope this is not just how this projector should be calibrated.

I found the problem...there is a white peaking setting that has to be set to 0. If it is any higher, the distortion kicks in. I'm just glad the projector didn't have any problems. I have been very happy with this unit.