The APRESYS S4210 combines professional-grade BaK4 phase-coated optics, a durable magnesium alloy body and ergonomic outdoor handling to deliver bright, sharp and naturally balanced viewing performance for birdwatching, travel and long-range outdoor observation.
- BaK4 phase-coated prism system for improved contrast and image sharpness
- Bright 10x42 optical configuration for versatile outdoor viewing
- Magnesium alloy body with ergonomic anti-slip rubber armor
- Enhanced color reproduction with reduced haze and glare
- Comfortable long-duration observation with reduced eye fatigue
- Waterproof outdoor construction for reliable field performance
- Twist-up metal eyecups for eyeglass-friendly viewing
- Fast center focus system with right-eye diopter adjustment
- Wide field of view for birdwatching and landscape observation
- Bright and balanced optical performance in changing light conditions
Bright and Natural Outdoor Viewing Performance
The APRESYS S4210 is designed for users who demand clear, comfortable and color-accurate viewing during outdoor observation.
Equipped with a professional BaK4 prism system and advanced phase coatings, the S4210 delivers brighter image transmission, sharper distant detail and improved contrast across the entire field of view.
Compared to standard binocular optics, the phase-coated prism design reduces haze and improves image transparency, producing a cleaner and more immersive viewing experience for birdwatching, wildlife observation and outdoor exploration.

Phase-Coated BaK4 Optics for Improved Clarity
The S4210 features high-performance BaK4 prisms with precision phase coatings that enhance optical efficiency and image definition.
This advanced optical system helps provide:
- Sharper distant object detail
- More balanced brightness distribution
- Reduced glare and internal reflections
- Improved contrast in complex lighting
- Cleaner edge definition across the image
Whether viewing mountain landscapes, moving wildlife or distant scenery, the S4210 maintains strong visual clarity with minimal softness or optical haze.

True-to-Life Color Reproduction
The optical coating system is engineered to improve color fidelity and viewing comfort during prolonged observation sessions.
The result is:
- More natural color rendering
- Higher color saturation without overprocessing
- Reduced washed-out highlights
- Better shadow detail separation
- More comfortable long-duration viewing
From forest environments to coastal landscapes, the S4210 produces a vivid and realistic outdoor image with balanced tonal performance.

Ergonomic Magnesium Alloy Construction
Built with a durable magnesium-aluminum alloy chassis, the S4210 combines structural strength with portable outdoor usability.
The ergonomic body shape and environmentally friendly rubber armor provide:
- Secure anti-slip grip
- Improved shock resistance
- Comfortable handheld operation
- Reduced hand fatigue during long observation sessions
The lightweight yet rugged body design makes the binocular highly suitable for hiking, travel and extended field use.

10x42 Optical Configuration for Versatile Observation
The 10x magnification and 42mm objective lens configuration deliver an excellent balance between viewing power, brightness and portability.
The S4210 performs exceptionally well for:
- Birdwatching
- Wildlife observation
- Nature exploration
- Outdoor sports viewing
- Landscape observation
- Travel and hiking
Its 6.1° field of view allows users to track moving subjects while maintaining strong situational awareness outdoors.

Comfortable Viewing for Extended Use
Designed for long-duration observation, the S4210 features 16mm eye relief and metal twist-up eyecups for comfortable viewing with or without eyeglasses.
The optical system is optimized to reduce visual fatigue by improving image consistency between both eyes and minimizing glare during extended outdoor sessions.
This creates a more relaxed and immersive observation experience even during all-day field use.

Waterproof Outdoor Reliability
The S4210 features a waterproof body structure designed for dependable outdoor performance in changing weather conditions.
Suitable for use in:
- Light rain
- Humid outdoor environments
- Forest trails
- Coastal conditions
- Travel and hiking environments
Its sealed optical structure helps maintain stable viewing performance during demanding outdoor activities.

Use Cases
Birdwatching and Wildlife Observation
The sharp 10x42 optical system and phase-coated prisms provide excellent clarity for observing birds and wildlife at medium to long distances.
Hiking and Outdoor Travel
The rugged magnesium alloy body and ergonomic handling make the S4210 highly portable for hiking and outdoor exploration.
Landscape and Nature Viewing
Balanced brightness, strong contrast and natural color reproduction create an immersive outdoor viewing experience.
Technical Specifications
| Specification |
Details |
| Model |
S4210 |
| Magnification |
10x |
| Objective Lens Diameter |
42mm |
| Exit Pupil |
4.2mm |
| Eye Relief |
16mm |
| Prism System |
DAHA BaK4 Phase Coated |
| Resolution |
6 |
| Near Focus Distance |
Under 2m |
| Brightness |
17.6 |
| Focus System |
Center Focus + Right Diopter |
| Field of View |
6.1° |
| Field of View @1000yds |
321ft |
| Weight |
720g |
| Dimensions |
127 × 151 × 51mm |
| Eyepiece Structure |
3 Groups / 4 Lenses |
| Objective Structure |
3 Groups / 4 Lenses |
| Eyecups |
Metal Twist-Up |
| Waterproof |
1m–5m |
Included in the Box
- APRESYS S4210 Binoculars
- Carrying Case
- Neck Strap
- User Manual