Ultrashort-throw projectors, also called UST and "laser TVs," are one of the most popular projector types on the market. These rectangular devices sit almost right against the wall, projecting upwards to create a huge image even in smaller rooms where a traditional projector can't fit. Even the best projectors would struggle making an image as big in as little space as what's possible with USTs. Their specs seem especially impressive, with some of the highest lumen ratings of any projector type.
However, that's not the whole story. There are significant compromises in all UST designs, such that their image quality is not always what it seems on paper. While all projectors work better with a screen, UST projectors basically require one because of how they project light. So the marketing claims of "easy TV replacement" are a little misleading. They're also hugely expensive. So are you paying more for similar or worse performance, and all for the promise of easier installation? Let's take a closer look.
What's a UST?
Epson
A traditional home projector can create a 100-inch image from a distance of around 10 feet. Depending on the lens, and if there's any zoom, it can be a few feet farther or closer to the screen. A regular short-throw projector -- not an ultrashort one -- can create the same size image from around 5 feet. An ultrashort-throw projector can create a 100-inch image from less than a foot from the screen. They do this using a lens with far greater complexity than what you'd find in other projectors.
Most UST projectors use the latest in projector tech, including laser light sources and 4K imaging chips. So UST projectors can have an impressive spec list -- most notably in terms of lumens, which are a measurement of brightness. Lumens are one of the most important differences between projectors. UST projectors are often rated for a lot of lumens, and since they're restricted in their image size due to how their lenses work, the images they create can be very bright.
Brightness isn't everything
Projecting an image directly on a painted wall like this would ruin the picture. Optoma
Let's first talk about those performance claims. All projector companies fudge their brightness numbers, sometimes a little, sometimes a lot. So, a 3,000-lumen projector is almost certainly not 3x brighter than a 1,000-lumen projector. Brighter? Probably, but it's not as obvious a difference as the numbers would suggest.
Anyway, this is only of secondary importance to what is the main determinator of picture quality: contrast ratio. This ratio is the difference between the brightest and darkest parts of an image. No projector has as good a contrast ratio as OLED or even the better LED LCDs. All UST projectors use the same imaging chips as regular projectors, so in the best case their contrast ratios are going to be the same. The elaborate lenses required for UST projectors to work typically reduce the contrast ratio in the models we've seen, so the overall image is going to be worse than far cheaper non-UST projectors. While the laser and LED light sources in many UST projectors can produce deeper, richer colors than what many traditional projectors can produce, lots of projectors are available with LEDs or lasers, negating that advantage.
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