ViewSonic PX748-4K throw distance & placement

The PX748-4K carries a zoom lens rather than a fixed or ultra-short-throw optic, and that is the single fact that shapes this whole preset. A zoom lens gives a range rather than a single mandatory distance: at 120 inches on a 16:9 screen, the projector can sit anywhere from 3.01 m to 3.91 m from the wall and still fill the frame correctly. That 0.9 m of latitude (a 1.3x zoom) is what lets a rear-shelf mount, a ceiling mount set back from a beam, or a rear-projection stand all remain valid options in the same room, rather than forcing one exact spot.

At 4000 lumens with native 3840x2160 resolution and a lamp light source, this projector suits a room where some ambient light control is possible but total blackout isn't guaranteed - a dedicated media room with curtains or blinds, rather than a sunlit family room used mid-afternoon. The lamp source means scheduled bulb servicing over the unit's life, which is a normal home-cinema maintenance rhythm rather than a drawback specific to this model.

Use the calculator by keeping this preset's 120-inch, 16:9 setting and dragging the screen-size slider up or down to see the throw window move with it - a bigger screen pushes both ends of the 3.01-3.91 m range further back, a smaller one pulls them closer. The zoom range itself is what gives you room to place the projector off dead-centre distance without needing lens-shift gymnastics.

What the calculator does not decide: it does not account for screen gain or a grey/ALR surface (which change perceived brightness independent of throw), it does not model ambient-light rejection for partially lit rooms, it says nothing about ceiling or rear-shelf mount hardware, and because the PX748-4K uses a fixed built-in lens rather than an interchangeable lens system, there is no separate lens-choice step to work through. Audio remains a wholly separate planning question the throw figures don't touch.