LG ProBeam BU50NST 4K DLP Laser Projector
Our Take

The LG ProBeam BU50NST's 4K UHD resolution and 5,000-lumen rated brightness make it a strong contender for boardrooms, conference rooms, and other applications that need fine detail in a big image that can stand up to ambient light.

Pros
  • 4K UHD (3840x2160) resolution using XPR fast-shift pixel shifting; supports HDR 10
  • Laser-phosphor light source promises up to a 20,000-hour lifetime
  • 1.6x zoom lens; vertical and horizontal lens shift
Cons
  • Lacks support for 360 degree orientation
  • No 3D support
LG BU50N front right

Most LG projectors to this point are meant for home or portable use. The 4K UHD (3840x2160), $4,499 LG ProBeam BU50NST laser projector is among the company's first targeted for business and education. For the most part, it's best described as the laser-based equivalent of a typical 5,000-lumen, lamp-based projector (which is how it is spec'd), and suitable for the same tasks.

Compared with most 5,000-lumen laser UHD projectors, the BU50NST is smaller, making it less obtrusive and easier to find room for. And although the documentation makes no mention of it, LG says the anti-dust optical engine and long-life laser light source make the projector virtually maintenance free. So while its natural home is a boardroom, large conference room or classroom, or small auditorium, the BU50NST is potentially useful also for applications like retail or museum displays and even sports bars.

 

Features

The BU50NST's small size—12.8 x 14.6 x 6.1 inches (HWD)—is one of its more appealing features. Note that it weighs 21.4 pounds however—about as much as most of its competitors. So while it will fit in a tighter space, it's not much easier to handle during setup. Some of its noteworthy features include HDR support, a built-in Web browser, support for DLNA, and support for wireless connection to mobile devices, so you can show presentations easily from a phone or tablet.

Note too that based on the BU50NST's 16:9 native aspect ratio, its HDR support, and some of its menu choices—which include a game mode, a Cinema Home mode, and LG's version of frame interpolation—you could be forgiven for thinking that it must be suitable for a brightly lit family room for movies, videos, and game playing. However, LG doesn't suggest it for that application, and in our tests, contrast and HDR shadow detail came up short for home use.

LG BU50N side
Vertical and horizontal lens shift controls are found on the side of the BU50NST.

Physical setup is straightforward. The BU50NST is designed to be placed either on a flat surface or inverted in a ceiling mount, and it offers flexible positioning thanks to its lens shift and 1.6x zoom. With the projector sitting on a table and the lens in its vertically centered position, the vertical shift is +/- 50% of the image height, while the horizontal shift is +/- 20% of the image width. If you need to correct keystone or other geometric distortion, a 12-point warp adjustment offers four-corner correction, one-point barrel distortion correction on each vertical edge, and two-point barrel distortion correction on each horizontal edge.

LG BU50N Remote

I measured the BU50NST's brightest predefined mode at 4,329 ANSI lumens—enough to light up a 170-inch diagonal, 16:9, 1.0-gain screen in moderately bright ambient light. Throw distance for a 170-inch image ranges from roughly 16.1 to 25.8 feet. (For the range for your screen size see the ProjectorCentral LG ProBeam BU50NST projection calculator.) And unlike the brightest mode in most projectors, which are best avoided because of obvious color shifts, the BU50NST's brightest mode delivered accurate enough color to make it our preferred choice for presentations unless they're heavily dependent on photorealistic images.

Note also that the BU50NST includes a pair of 5-watt stereo speakers, which deliver good enough sound quality to make them worth using, along with high enough volume for a medium to large size room. If you prefer to use an external audio system, one of its HDMI ports supports HDMI-ARC, and there's a 3.5mm analog audio out port and Bluetooth speaker support with an AV sync control.

Here's a more complete list of the BU50NST's key features:

  • 3840x2160 (4K UHD) native resolution with a 0.47-inch DLP chip using XPR pixel-shifting
  • HDR10 support
  • Laser-phosphor light source
  • 5,000 ANSI lumen rating
  • Up to 20,000 hour light-source life
  • 3,000,000:1 dynamic contrast ratio rating
  • 24/7/365, virtually maintenance-free operation
  • Frame interpolation for smoothing motion
  • DICOM simulation mode for medical education and presentations
  • 1.6x zoom lens; 1.32:1 - 2.11:1 throw ratio
  • Generous lens shift: ± 50% vertical; ±20% horizontal
  • Advanced edge adjustment with 12-point warping adjustment, including 4-corner correction
  • Compact size; 21.4 pounds
  • Digital inputs include HDBaseT and 2 HDMI 2.0b (HDCP 2.2) ports
  • HDMI-CEC support for control of connected sources
  • IP Control
  • Built-in WiFi with WebOS browser app
  • Smart Connection feature for easy wireless connection for screen sharing; supports Miracast and DLNA
  • USB input with integrated media player
  • Onboard 5-watt stereo speakers; HDMI-ARC; audio out port; supports Bluetooth audio out with AV Sync adjustment
  • Full-size remote
  • Limited 3-year warranty (all parts and labor including light source)
 

Performance

The BU50NST offers eight predefined color modes for SDR (standard dynamic range) input. Except for DICOM, the SDR modes all deliver nicely saturated, vibrant color for graphics straight out of the box. However, some hues were a little off. Yellow, for example, was a bit darker than it should be in most modes—a common issue for DLP projectors.

Presentation is the brightest mode, and my preferred choice for presentations that don't include photos. Green was blue-shifted, as demonstrated by a patch of turquoise in one image that turned distinctly blue. However, yellows and reds were green shifted compared with the other modes, giving an overall green bias to many images compared with other modes. Still, it was not enough of a bias for most people to notice without the comparison, much less find annoying. In photorealistic images, Presentation mode tended to lose the subtle gradations that give faces and other rounded objects a sense of three dimensionality.

The second brightest mode, and my preferred choice for presentations that include lots of photos or video, is Standard. It also shifts greens toward blue, but not by as much as Presentation mode, and most people aren't bothered much by a blue shift in any case. More important, it didn't add a green shift for yellow, and it did a better job of showing subtle gradations. Cinema did a still better job of maintaining gradations and offers a darker black level. However it delivers far lower brightness than Standard mode.

LG BU50N Lifestyle 1

HDR Effect mode delivered basically a higher brightness version of Cinema mode, with similar color accuracy, ability to hold gradations, and black level. However, its higher brightness gave presentations noticeably better contrast for graphics with black backgrounds and gave photorealistic images in darker scenes both better contrast and improved shadow detail. The combination makes it the preferred choice for video and film.

The only other notable SDR mode is DICOM, which is really a DICOM Sim mode, meant for viewing medical images like MRIs strictly for education and presentation purposes, rather than diagnostic use. Game mode was a close match to Standard mode, Expert (Dark Room) was all but indistinguishable from Cinema mode, and Expert (Bright room) fell somewhere between Cinema and Standard modes for maintaining gradations and color accuracy, but without the darker black levels of Cinema Mode.

HDR Preset Modes. When the BU50NST detects HDR input, it automatically replaces the menu list of SDR color presets with five HDR presets. One shortcoming all the HDR preset modes have in common is low contrast, irrespective of attempts to optimize related picture adjustments (Black Level, Dynamic Contrast, etc.). Another, surprisingly, is that none of the HDR modes delivered anything like the level of shadow detail that the HDR Effect mode delivered with SDR content.

The HDR Presentation mode is the brightest mode in lumens and offered the brightest looking yellow. The combination gave an overall sense of bright, vibrant color to most images. However, Presentation mode also lost the subtle gradations that give photorealistic images a more three-dimensional look, which makes it the preferred choice only for HDR presentations that have few or no photos or video clips.

HDR Standard mode delivered brighter, more vibrant color than any mode but Presentation, and it held gradations a little better. That's enough to make it the preferred choice for HDR Presentations with photorealistic images as well as for HDR video and film.

The other three HDR modes are hardly worth considering for the kind of application a 5,000-lumen projector is meant for. Cinema Home mode held gradations a bit better than Standard mode, but at much lower brightness. Cinema mode also handled gradations well, but its blue and magenta were much less saturated than in any other mode, and it had the lowest contrast in my tests of any HDR mode. Game mode delivered a slightly blue shifted green compared to the other modes, and a slightly less saturated magenta than all but Cinema mode.

Viewing Film and Video

SDR Viewing. I tested the BU50NST with a variety of movies on Blu-ray discs as well as movies and scripted shows on Netflix. I watched primarily with ambient light, since that's how the projector is most likely to be used, and did some additional testing in a dark room. In all cases, the image was quite watchable. Most people will consider it more than acceptable for presentations that include video clips and even for an occasional full length movie in a conference room, classroom, or special event in school, museum or similar setting.

The key shortcoming for photorealistic images, as with most business projectors, is noticeably low contrast. Color accuracy is good enough that in scenes I'm familiar with, including the opening song and dance on the highway in La La Land, the projector delivered vibrant hues, most of which looked mostly spot on. But it lacked the extra pop that comes from good contrast—and I couldn't find any setting to improve it. Viewing it on my Screen Innovations Slate 1.2 ALR screen—with its gunmetal gray color—improved contrast only a little.

LaLaLand-4
La La Land showed off the vibrant color on the BU50NST, but it missed some pop you'd see on a home theater projector with better contrast.

That said, the HDR Effect mode held shadow detail impressively well for a business projector even in ambient light. In one of my go-to dark scenes in Batman v Superman, in what will later become the Batcave, it didn't deliver as dramatic an image as I'd expect from a home theater projector, but even in moderately bright ambient light, I could see the outlines of individual bats hanging upside down in the dark. Lowering the light level or adding the ALR screen into the mix improved the shadow detail even more. And when I did both, the scene began to approach the visually dramatic image it should be.

4K UHD HDR Viewing. For HDR viewing tests, I used the HDR disc versions of some of the same movies I looked at using 1080p SDR Blu-ray discs, and also the Spears & Munsil UHD HDR Benchmark. The good news is that the projector handled switching back and forth between SDR and HDR input seamlessly and it did a good job delivering the higher resolution it promises with 4K UHD material. On the closeup of a peacock feather in the Spears and Munsil Benchmark's demo video, not only did the individual barbs of the feather (the strands sticking out from the central stem) stand out clearly, so did the even smaller barbules on the barbs.

As already mentioned, none of the HDR modes do as good a job with shadow detail as the HDR Effect mode does with SDR input—a statement that held true even when using the SI ALR screen. And as with SDR input, contrast was middling at best, while color accuracy was good enough for almost anyone to find acceptable. In short, the BU50NST can show fine detail appropriate for the resolution, and deliver a highly watchable, but not impressive, 4K HDR image.

Conclusion

The LG ProBeam BU50NST's small size makes it less obtrusive than its competition if it's sitting in the open, and easier to fit in a tight space for applications like retail or museum displays.

LG BU50NST Lifestyle2

In our tests, the projector delivered 4,329 ANSI lumens in its brightest mode—a respectable 87% of its 5,000 ANSI lumen rating. More important, the highest-brightness mode delivered far closer to neutral color than the highest brightness modes in most projectors, making it not only usable, but our preferred mode for presentations with few or no photorealistic images. Even the preferred mode for when photorealistic images are included came in at 3,267 lumens, which is enough to light up a 145-inch diagonal 1.0-gain screen in moderately bright ambient light.

Very much on the plus side, switching between SDR and HDR input works smoothly. And despite somewhat low contrast, both SDR and HDR modes offer good enough color accuracy to be a more-than-acceptable choice for watching a full length movie in a business or education setting, not to mention short video clips in a presentation. The projector also delivers the fine detail it should with 4K input. And at its $4,499 cost, it's one of the lower-priced UHD-resolution models in its brightness class. All this makes the LG ProBeam BU50NST a serious contender among 4K, 5,000-lumen business projectors and—considering its size—one of those proverbial good things that comes in a small package.

Measurements

Brightness. The BU50NST's 5,000-lumen brightness rating comes with the hedge that the rating is based on the perceived brightness being equivalent to the brightness of a 5,000-lumen lamp-based projector. However, the difference between perceived and measured brightness is moot in this case, since the measured ANSI lumens was a solid 87% of the rating.

The BU50NST offers three Energy Saving settings: Maximum (full power), Medium, and Minimum. With the 1.6x zoom lens set to its widest angle setting, the measured ANSI lumens in each power mode was as follows for each color mode:

LG ProBeam BU50NST ANSI Lumens

Mode Minimum Medium Maximum
Presentation 4,329 3,528 2,783
Standard 3,267 2,662 2,100
Cinema 1,651 1,345 1,061
DICOM 2,295 1,870 1,475
Game 3,261 2,657 2,096
HDR Effect 2,143 1,746 1,377
Expert (Bright Room) 2,353 1,918 1,513
Expert (Dark Room) 1,536 1,252 987

Zoom Lens Light Loss: The 1.6x zoom reduces brightness by 7%.

Brightness Uniformity (Wide Zoom): 81%

Brightness Uniformity (Telephoto): 84%

Lowest Measured Input Lag (1080p): 61 ms

Lowest Measured Input Lag (4K): 173 ms

Rainbow artifacts. I saw rainbow artifacts only occasionally and only in video and film content when testing the BU50NST. Our usual warning applies, however. If you're concerned about rainbow artifacts, be sure to buy the projector from a source that will allow easy returns, so you can test it out for yourself.

Fan Noise. LG rates the BU50NST's fan noise at 26 dB in Maximum Energy Savings mode, 27 dB in Medium mode, and 29 dB in Minimum Energy Savings mode. Even 29 dB is a low rating for a 5,000-lumen laser projector, so this counts as a plus overall. But note that both Minimum and Medium mode are easy to hear in a quiet room from at least 20 feet away and even the Maximum mode is noticeable from 15 feet.

LG recommends using High Altitude mode at 3,937 feet and above. In my tests, the fan noise at each power level setting wasn't much higher with it on, so unless you need a quiet enough room to insist on acoustic isolation for the projector when High Altitude mode is off you probably won't need it when the mode is on either.

Connections

LG BU50N connections
  • HDMI 2.0b with HDCP 2.2 (x2, one with ARC)
  • HDBaseT (for video, audio, control)
  • LAN (for built-in Web browser, DLNA, IP control)
  • 3.5mm stereo analog audio out
  • USB 2.0 Type A (x2) (For reading files from USB memory key; connecting keyboard, mouse, or gamepad
  • RS-232 (control)
  • Bluetooth speaker out with AV Sync
  • Built-in WiFi for network connection and to facilitate sharing via LG smartphone and computer apps, integrated web-browsing and video streaming

For more detailed specifications and connections, check out our LG ProBeam BU50NST projector page.

To buy this projector, use Where to Buy online, or get a price quote by email direct from Projector Central authorized dealers using our E-Z Quote tool.

Comments (2) Post a Comment
Steve Frank Posted Aug 23, 2020 4:05 AM PST
Very long review & full of details.

Is there any plan to review the Optoma GT1090HDR?
Rob Sabin, Editor Posted Aug 24, 2020 7:53 AM PST
Yes, we have a sample coming soon for review of the Optoma GT1090HDR. For those unaware, this is a 1080p resolution laser-driven home theater and gaming projector. We're hopeful it'll be a nice alternative to lamp-driven models that retains decent contrast for its brightness class and other characteristics we hold dear like good color gamut and good out of box color accuracy.

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