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Posted on November 11, 2020 by Phil Jones

LG BU50NST 4K Laser Business Projector Review – Performance: Brightness, Contrast, Audible Noise


LG BU50NST Brightness: 4810 Lumens

Color ModeLumens
HDR Effect3724
Expert (Bright Room)3522
Expert (Dark Room)2715

LG BU50NST has a rated brightness of 5,000 lumens. I took 3-4 readings about 15-20% out from the center of the lens which usually gives a pretty good approximation of ANSI lumens. At full wide angle I measured the BU50NST in its brightest picture mode, BRIGHT, with the lamp power set to Minumum.

LG BU50NST Brightness: 4810 Lumens

At wide zoom, High-Bright mode, the BU50NST measured 4,810 lumens which was slightly below LG’s brightness claim. I also measured the other seven available modes.


LG has specified a contrast ratio of 3,000,000:1, which is quite remarkable, however it is important to recognize the reality of results vs specs. In reality, a projector such as this has the ability to display a high contrast image in a wide range of lighting conditions with a variety of screen surfaces. Any comparison of this design, which is intended for commercial applications, to a design intended for dark theater usage would be in like comparing the torque of a Semi-truck to a sports car. Two different tools for two different purposes and while they can both do a lot of the same stuff such as cruise on the highway, each has its place and purpose. That the BU50NST has such high output capabilities combined with a wide range of output modes allows for the result of a high contrast system in a very wide range of applications.

For evaluation, we looked at some footage from the Apple TV+ program Tiny World. The pictures below show the various picture modes and reveal that despite the mode chosen, the image maintained contrast in the dark hairs of the zebra as well as the whites in the adjacent stripes. This is a result that I would not expect on a bright color wheel lamp based projector of similar output capabilities. This is partially due to the inherent capabilities of DLP coupled with Laser Phosphor illumination, however LG has done a fine job of leveraging the core technology to a great result.

While I did not expect to find this LG Business Solutions model to be comparable to models designed for theater usage, I was quite surprised at the result when sitting in full darkness and viewing film content. By using the appropriate dark room mode and setting the Energy Conservation (laser power) to the lowest output choice, I was surprised by the viewing experience. It was quite good with color accuracy out of the box that is admirable. Combined with the ability to store video modes and settings by input, the BU50NST could easily slip into “movie mode” when installed in a conference room after the sun goes down or with the shades drawn for those rare occasions when that might be needed. Alternatively, if this were installed in a home where it would most often be viewed in a media room, with some to significant ambient lighting, the results would be remarkable when paired with an ambient light rejecting screen. There was no question amongst those who viewed this in our bright room set up, as to the attraction of the large bright image the BU50NST delivered. LG recognized this capability and as such is offering consumer version of this design intended for residential installations.


The fan noise produced by BU50NST is lower than typical 5,000 lumen projectors with a rated SPL of 26, 27, or 29 dB, depending on Energy Saving mode with the highest energy saving also being the quietest. I found the sound to be unnoticeable in my less-than-silent environment which probably is similar to many non-theater applications. Specifications and measurements are of little value in the real world where the timbre and placement of the cooling noise is often more influential than the rated volume.

I expect this to be less noisy in real world applications than nearly any 5000-lumen lamp based projector as well as many competitive laser-based systems. The only other operational noise I observed was when selecting a mode that adjusted the motorized iris. While this noise is audible, it is momentary and in response to a setting change so it is really of no concern. Actually, the fact that LG included this feature and also incorporated it into the picture mode presets shows how thoughtfully designed the BU50NST is.

LG BU50NST Specs

Projector Model BU50NST
Technology DLP with XPR (0.47” DMD)
Price $4499
Brightness (Manufacturer Claim) 5000
Brightness Description Perceived when compared to lamp based measurements
Contrast Ratio 3,000,000:1
Projection DLP w/Laser light source, DLP w/Laser light source-1
Native Resolution 3840x2160
Max Resolution 4096 x 2160
3D No
Blue Ray No
Ultra Short Throw No
Native Aspect Ratio 18
Video Compatiblity
HDTV 720p, 1080i, 1080p, UHD, 4K
Lamp Life 20,000 hours (Normal mode)
Noise Level (-db) 26 - 29 depending on energy mode
Audio 5-Watt X 2
Power Zoom Focus No
Lens Shift Yes
LAN Networking Yes
Zoom Lens Ratio 1.6
Optional Lens No
Classroom Yes
Speakers No
Special Features HDBaseT, WebOS, Screen Sharing, Content Sharing
Wireless Networking Yes
Dimensions 14.6“ W x 6.1” H x 11.4” D
Weight 21.4 lb
Warranty 3 years
Year 2020

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