There was a difference in brightness between our test units. Optoma rates both models at 2400 ANSI lumens, but we measured the UHD51A at 1,690 lumens in its brightest color mode compared with 1,998 for the UHD50. Even so, the UHD51A is bright enough with video-optimized settings to light up a 175″ 1.3-gain screen in a dark room or a 110″ screen with moderate ambient light.
Optoma UHD51A Performance
Brightness
With the zoom lens on our test sample at its widest angle setting, we measured ANSI lumens for Bright and Eco power modes as follows
Low Lamp Mode
Eco mode lowers brightness by about 33% compared with the full power setting.
Zoom Lens Light Loss
The 1.3x zoom lens drops brightness by only about 12% in the full telephoto setting, which is little enough to ignore in most cases when deciding how far to place the projector from the screen for a given size image.
Color Brightness
The UHD51A performs well on color brightness tests. Even in the Bright mode the color output measures 80% of white, and in all other presets it exceeds 85%.
Brightness Uniformity
The measured brightness uniformity for the UHD51A is 63% at the wide-angle end of the lens and 68% at the telephoto end–a little low for a home theater projector in this price range. With a solid white test image, there’s minor visible fading on the left and rightmost 5% to 10%. Those who are particularly aware of low uniformity may find it bothersome. Others will never notice it because the brightness change isn’t obvious and it is on the edges of the image which you rarely focus on.
Video Optimized Lumens (SDR)
Even with default settings, color in Cinema mode is well within a realistic range, although moderate tweaking of Color Matching settings gives more accurate color. The more important issue with the defaults is low contrast and lack of three-dimensionalities, which are easily fixed by adjusting brightness and contrast. After adjustments, black is suitably dark; contrast, shadow detail, and three dimensionalities are all excellent; and brightness is unchanged.
The measured 1,153 lumens with optimized settings is enough to fill a 175″ 1.3-gain screen in a dark room. Eco mode’s 769 lumens is enough for a 145″ screen, and it gives you the flexibility to move to Bright power mode as the lamp loses brightness with age. For rooms with ambient light, the video optimized settings with Bright power mode can still light up a 110″ screen.
Color Preset Mode Performance
The UHD51A’s Cinema mode is its second brightest mode. Game and Reference modes both deliver a touch lower brightness, with color that’s similar in hue but less saturated. HDR Sim is just a little green-shifted, but nowhere near as much as the brightest mode.
As with most projectors’ brightest modes–Bright mode has an obvious green bias. Unlike many DLP models, changing the Brilliant Color setting to 1 (which is off) from the default 10 doesn’t improve color accuracy enough to matter. If you need the extra brightness to combat ambient light you may be willing to use it occasionally if you don’t mind the green tint.
Frame Interpolation
The UHD51A’s FI offers three settings besides Off. The factory default setting is Low, which smooths motion enough to notice while still showing a bit of judder in pans or an object moving across the field of view. However, there’s little-to-no digital video effect, which leaves nothing to gain from turning it off. Unlike the maximum setting in many projectors, High doesn’t smooth motion entirely, but it also adds only a minor digital video effect. You might prefer a more aggressive version of FI for live and recorded video, but this more subtle version is better for the film.
4K HDR Performance
Unlike some 4K projectors, the UHD51A handles the switch from SDR to HDR input and back again fully automatically. When it detects HDR, it switches to HDR color mode as the only choice. When it detects SDR, it switches back to whatever color mode it was previously set to.
SPECIFICATIONS
- SPEC3840x2160 resolution (4K UHD) for fine detail and crisp images
- Allows voice-activated control through Alexa
- RGBRGB color wheel delivers excellent color accuracy
- HDR with choice of four highly watchable modes; HDR 10 compatible
- Supports DCI-P3 wide color gamut, REC.2020, and REC.709
- Frame Interpolation to smooth motion; choice of three levels
- Two HDMI 2.0 ports with 4K UHD, HDR support
- 1.3x zoom lens
- Modest vertical lens shift
- Full 3D with DLP Link glasses
- 4000-hour lamp life with full power, 10,000 hours in Eco mode, 15,000 hours in Dynamic mode
- Replacement lamps are $19
- Two 5-watt stereo speakers deliver good sound quality and high enough volume to fill a small to mid-size room.
