The BenQ’s “iris action” – no, there’s no dynamic iris, but, instead, its LED dimming is reasonably good.
It’s not the least detectable out there, but rarely offends. I tend to notice this kind of behavior more than others because I’m a black level fanatic. Whether by mechanical iris, or as in this case, using the light engine to lower overall brightness on non-bright scenes, that calls for some serious “iris action.”
I do spot some slowness in mid-brightness scenes, for example, where the movie is cutting back and forth between two people talking with the same background, but one in a nice bright white shirt and the other in one less bright. You can catch the slight darkening of the overall scene when the camera is on the person with the darker shirt. But, it’s never jerky, so most folks won’t notice anything, or will simply assume that’s the way the movie was shot.
On the downside, BenQ isn’t dramatically lowering brightness levels on really dark scenes, so that the overall black level performance is only “good” and not close to, say, the Epson UB projectors, or even remotely close to any of the JVCs. It should be about comparable to the new Sony 4K VW385ES, a true 4K projector, although lamp based, that list prices for slightly less. More comments on the black level performance, of course, in the Picture Quality section.