Shelby_Compare
Member
There is a thread going around from someone with a 5050UB on a 120 inch fixed frame in a properly dark room, feeding it discs from a UB820. His complaint is not brightness, he says he never wants more of it, it is that blacks in dark films do not sit down the way he wants. He has left the auto iris on and never really thought about it, and he has noticed JVC owners deliberately running the aperture partly closed once they have light to spare.
That instinct is right. A lens iris cuts light before it ever reaches the imaging panels, so it lowers the black floor and lifts measured on and off contrast in a way no picture setting can. If you genuinely have lumens to spare on a 120 inch screen, spending some of them on a lower black floor is a good trade.
Two things to know before you do it. The auto iris is not the same thing. It modulates scene by scene, and on slow fades some people see it working, which is more distracting than a slightly raised black. A fixed setting is boring and consistent, and boring wins in a dedicated room. Second, HDR eats the headroom you thought you had, so if your projector keeps separate memories per mode, close it down for SDR and leave it open for HDR rather than picking one compromise.
And before any of it, look at your ceiling and side walls. In most rooms called dedicated the black floor is set by light bouncing off a white ceiling back onto the screen, not by the projector. Closing the iris will not fix a room that is throwing the picture back at itself.
What setting did people land on, and did you measure the on off contrast either side of the change or just go by eye?
That instinct is right. A lens iris cuts light before it ever reaches the imaging panels, so it lowers the black floor and lifts measured on and off contrast in a way no picture setting can. If you genuinely have lumens to spare on a 120 inch screen, spending some of them on a lower black floor is a good trade.
Two things to know before you do it. The auto iris is not the same thing. It modulates scene by scene, and on slow fades some people see it working, which is more distracting than a slightly raised black. A fixed setting is boring and consistent, and boring wins in a dedicated room. Second, HDR eats the headroom you thought you had, so if your projector keeps separate memories per mode, close it down for SDR and leave it open for HDR rather than picking one compromise.
And before any of it, look at your ceiling and side walls. In most rooms called dedicated the black floor is set by light bouncing off a white ceiling back onto the screen, not by the projector. Closing the iris will not fix a room that is throwing the picture back at itself.
What setting did people land on, and did you measure the on off contrast either side of the change or just go by eye?
