Optoma UHD35STx

The Optoma UHD35STx is a 4K projector with a short 0.5:1 throw ratio, delivering a 100-inch image from roughly one meter away. It’s based on DLP technology and offers a quoted brightness of 3,600 lumens. Designed for versatile use, it supports HDR10 and HLG, and features a gaming mode with 4.2 ms latency and a refresh rate up to 240 Hz in Full HD. This positioning makes it suitable for both gaming and cinematic content, especially in spaces where a traditional throw projector is impractical.

A compact concentration of DLP technology

At the heart of the UHD35STx is Texas Instruments’ DLP (Digital Light Processing) technology, using a 0.47-inch DMD chip equipped with millions of micro-mirrors. Each mirror, only a few micrometers in size, can tilt thousands of times per second to direct or block light to the lens. This architecture enables 4K UHD resolution via XPR (eXpanded Pixel Resolution), which rapidly shifts pixels to generate 8.3 million distinct pixels on screen, in line with the Consumer Technology Association standards for True 4K certification.

The compact 315 × 270 × 118 mm chassis and lightweight 3.5 kg build conceal a sophisticated optic with a 7.51 mm focal length. This short-throw optical design projects massive images while positioning the projector very close to the screen. The native 116% offset means the image is projected above the lens level, making it easy to place on a coffee table without visual obstruction. Bi-directional keystone correction (±40° horizontal and vertical) provides valuable installation flexibility in tight spaces.

The 8-segment RGBWRGBW color wheel is crucial to image quality. This configuration optimizes both brightness and color fidelity, balancing punchy whites needed for bright rooms with sufficiently accurate color for movies. The BrilliantColor system, adjustable from 1 to 10, lets you fine-tune the image according to the environment and content.

Brightness performance and dynamic contrast management

With 3,600 ANSI lumens, the UHD35STx is well suited to bright living rooms and daytime use. This output helps maintain a viewable image even with moderate ambient light—ideal for daytime gaming sessions or family sports viewing. The 240 W lamp offers three modes: Bright (4,000 hours), Eco (10,000 hours), and Dynamic (15,000 hours), allowing you to balance power consumption and longevity.

Dynamic Black is particularly noteworthy. Unlike a mechanical dynamic iris, this system electronically adjusts lamp power based on on-screen content. Dark scenes benefit from reduced brightness for deeper blacks, while bright scenes leverage full power. This real-time modulation contributes to the quoted 1,000,000:1 dynamic contrast ratio, although native contrast is naturally more modest—an inherent characteristic of single-chip DLP projectors.

Dynamic mode is a smart compromise between performance and lifespan. By automatically modulating brightness to content, it significantly extends lamp life while maintaining satisfying image quality. This intelligent light management is paired with low operating noise, ranging from 24 dB at minimum to 28 dB at maximum, enabling distraction-free viewing.

High-performance gaming: beyond the spec sheet

The UHD35STx’s gaming prowess is its standout differentiator. At 4.2 ms in 1080p at 240 Hz, its latency sets a benchmark in its price class, rivaling dedicated gaming monitors. This near-instant responsiveness virtually eliminates perceptible lag between player input and on-screen action—crucial for competitive shooters or titles requiring precise reflexes.

Enhanced Gaming mode goes beyond mere latency reduction. It disables certain image processing for faster response while enhancing visibility in dark areas. This tailored calibration reveals critical shadow detail, a meaningful tactical advantage in many modern games. The projector maintains a respectable 16.9 ms latency at 4K 60 Hz, low enough for smooth gameplay even at maximum resolution.

Compatibility with the latest consoles (PlayStation 5, Xbox Series X/S) is thoughtfully addressed. Players can choose 1080p at 120 Hz for maximum fluidity or 4K at 60 Hz for higher detail. This flexibility lets you tailor output to the game type: competitive titles benefit from higher frame rates, while narrative or exploration games shine in 4K.

HDR technologies and advanced color processing

Support for HDR10 and HLG (Hybrid Log-Gamma) transforms the experience with compatible content. Optoma’s HDR tone mapping analyzes and optimizes each frame to maximize available dynamic range. Highlights retain detail without clipping, while dark areas reveal nuances otherwise invisible. This sophisticated HDR handling partially mitigates the inherent native contrast limitations of single-chip DLP.

The Color Management System (CMS) enables fine adjustment of each primary and secondary color. While coverage of the Rec.709 color space isn’t complete by some independent measures (around 82% in certain tests), the projector offers enough flexibility to achieve pleasing results after calibration. ISF Day and Night modes, unlockable by a certified calibrator, let you save optimized presets for different lighting conditions.

Optoma’s Amazing Color technology integrates multiple processing algorithms to enrich color rendering. The processor analyzes content in real time to adjust saturation and hue based on scene type. This adaptive approach delivers vibrant colors for animation and video games while preserving natural skin tones for films and series.

Flexible installation and practical considerations

The UHD35STx’s short throw solves many common setup challenges. In apartments where space between sofa and wall is limited, it can sit on a coffee table or low shelf without casting distracting shadows when people move around. This setup also removes the need for a complex ceiling mount, reducing cost and complexity.

The lack of optical zoom (fixed 1.1x factor) and lens shift demands careful placement planning. Throw distance must be calculated precisely for the desired screen size, with limited wiggle room. Digital corrections (keystone, digital zoom) can partially compensate, at the cost of slight sharpness loss. The digital image shift feature still allows fine positioning without physically moving the projector.

Dual HDMI 2.0 inputs support HDCP 2.2, ensuring compatibility with protected 4K sources. The 1.5 A USB-A port can power a streaming dongle directly, eliminating a separate power supply. Audio outputs (3.5 mm and S/PDIF) provide connections to external audio systems, offsetting the limitations of the built-in 10 W speaker—adequate for casual use but not ideal for serious home theater setups.

Technical Specifications

Display and image

• Display technology: DLP
• Native resolution: true 4K UHD (3840 × 2160)
• Brightness: 3600 lumens
• Dynamic contrast: 1,000,000:1
• Native aspect ratio: 16:9 (compatible 4:3)
• Keystone correction: horizontal ±40°, vertical ±40°
• Supported frequencies
  • Horizontal: 31 to 135 kHz
  • Vertical: 24 to 120 Hz
• Uniformity: 80%
• Image size: 0.93 to 7.63 m (36.43” to 300.53”)

Optics and projection

• Throw ratio: 0.5:1 (short throw)
• Projection distance: 0.4 to 3.3 m
• Zoom: fixed
• Focal length: 7.51 mm
• Lens shift: vertical +0%
• Native offset: 116%
• 100” projection from just 1 m away

Gaming performance

• Ultra-low input lag
  • 4.2 ms (1080p at 240 Hz)
  • 16.9 ms (4K at 60 Hz)
• 3D compatibility: Full 3D (Frame-pack, 1080p24 / 720p50/60)

Connectivity and audio

• Inputs: 2 × HDMI 2.0
• Outputs: 1 × 3.5 mm audio, 1 × S/PDIF, 1 × USB-A Power (1.5 A)
• Control: 1 × RS232, 1 × 12V trigger
• Built-in speaker: 1 × 10 W

Light source

• Type: lamp (240 W)
• Lifespan
  • Bright mode: 4000 hrs
  • Dynamic mode: 15000 hrs
  • Eco mode: 10000 hrs

Power and consumption

• Power: 100 to 240 V, 50 to 60 Hz
• Power consumption
  • Standby: 0.5 W
  • Minimum: 220 W
  • Maximum: 320 W

Dimensions and ergonomics

• Dimensions (W×D×H): 315 × 270 × 118 mm
• Net weight: 3.5 kg
• Gross weight: 4.68 kg
• Noise level: 24 dB (min) to 28 dB (max)
• Remote control: backlit
• Security: Kensington lock slot, password, security bar

Compatibility

• PC formats: UHD, WQHD, WUXGA, FHD, UXGA, SXGA, WXGA, HD, XGA, SVGA, VGA, Mac
• Video formats: 480i/p, 576i/p, 720p, 1080i/p, 2160p (50/60 Hz)
• On-screen menu languages: 9 languages (French, English, Spanish, German, Japanese, Chinese)

Box contents and general information

• Included
  • UHD35STx projector
  • Backlit remote + 2 × AAA batteries
  • AC power cable
  • Basic user manual

Key features

• Ultra-detailed 4K UHD (3840×2160) resolution
• 100” projection from just 1 m (short throw)
• Low latency: 4.2 ms (1080p240Hz) / 16.9 ms (4K60Hz)
• 3600 lm brightness, 1,000,000:1 contrast
• Built-in 10 W speaker
• Dual HDMI 2.0, USB power, audio & S/PDIF
• Backlit remote control