Hanwha SLA-T-M940DN 12MP DC-Iris Varifocal Lens
The Hanwha SLA-T-M940DN is a professional varifocal lens engineered for high-resolution surveillance systems that demand sharp imagery across shifting light conditions without manual refocus or iris adjustment. Built around a 9-40mm focal length and rated for up to 12MP sensors, this DC auto-iris lens adapts automatically to ambient light, eliminating the need for operator intervention or scene-specific tuning. The F/1.5 maximum aperture combined with IR-corrected optics enables reliable operation in both daylight and infrared-illuminated environments, making it a practical choice for perimeter, retail, and industrial surveillance where continuous operation across day/night transitions is the norm.
Key Features
- 9–40mm Varifocal Range: Provides flexible framing from wide coverage to targeted detail—adjust focal length without swapping lenses, reducing installation time and spare parts inventory.
- 12MP and True 4K Support: Paired with a compatible 12MP sensor, this lens delivers the resolution needed for license plate capture, facial detail, or wide perimeter monitoring without optical softness or vignetting.
- F/1.5 DC Auto-Iris: The iris adjusts automatically to incoming light, preventing overexposure in bright scenes and maintaining sensitivity in dim lighting—no manual stop adjustment or scene-dependent configuration required.
- IR-Corrected Optics: The lens is optimized for both visible-light and near-infrared (850nm) wavelengths. Day imagery remains color-accurate; night vision with IR illumination is sharp and clear without the color-shift artifacts common in uncorrected optics.
- CS Mount, 1/3" to 1/2.5" Sensor Compatibility: Fits standard surveillance camera bodies across a range of sensor sizes, simplifying integration into existing or new deployments.
- Compact Form Factor, Under 50mm Length: Space-constrained installations—tight ceiling mounts, perimeter domes—benefit from the small footprint without sacrificing optical performance.
- Extended Temperature Operating Range: Rated -20°C to +60°C (-4°F to 140°F), this lens handles outdoor installations in cold climates and unheated warehouses without optical degradation or mechanical stiffness.
- Non-Condensing Humidity to 70%: Suitable for humid environments (loading docks, greenhouses, coastal facilities), though full waterproofing depends on the host camera housing.
- 2.5m to Infinity Minimum Focal Distance: Focuses from 2.5 meters onward, making it suitable for wide perimeter views and close-range monitoring of entry points or merchandise.
Integration and Compatibility
The SLA-T-M940DN integrates with any Hanwha IP camera or compatible third-party surveillance camera featuring a CS mount and 1/3" to 1/2.5" sensor. Verify sensor size and mount type before procurement—a 1/2" sensor will vignette if the lens is designed for a 1/3" format, and an M12 mount camera cannot accept a CS lens without an adapter. When paired with network video recorders or IP camera selection guides, this lens supports day/night surveillance workflows where automated iris control and IR correction eliminate manual intervention during light transitions. Consult your camera manufacturer's lens compatibility matrix to confirm optical and mechanical fit.
Deployment Scenarios
Deploy this lens in perimeter fencing, warehouse loading docks, retail environments, and financial institutions where high resolution and continuous automated operation are required. The 9-40mm range accommodates both wide-area coverage and detailed monitoring in a single camera position, reducing deployment footprint. For 24/7 outdoor installations, the IR correction and DC auto-iris combination delivers consistent imagery regardless of ambient light, reducing alert fatigue and false triggers caused by exposure inconsistency.
When to Consider a Different Lens
If your deployment requires fixed focal lengths and lower cost, review fixed-length alternatives in the Hanwha lens catalog. For ultra-wide coverage (angles wider than the 9-40mm varifocal can deliver), a dedicated wide-angle fixed lens may be more cost-effective. If active infrared illumination is unavailable and night vision is required, confirm your camera's built-in IR LEDs are sufficient; IR-corrected optics optimize IR illumination but do not generate it.
Frequently Asked Questions
Q: Is the SLA-T-M940DN compatible with my existing surveillance camera?
A: The SLA-T-M940DN uses a CS mount and supports 1/3" to 1/2.5" sensors. Check your camera's mount type and sensor size in the manufacturer's documentation. If your camera uses M12, C-mount, or a different standard, an adapter is not recommended—compatibility is not guaranteed.
Q: Does the DC auto-iris work without power?
A: No. The DC auto-iris requires a 12V DC power supply connected to the lens. If your camera does not provide DC power to the lens, you will need a separate power injector or a camera model that supports DC-iris lenses natively.
Q: Can I use this lens indoors and outdoors?
A: Yes. The lens operates from -20°C to +60°C and handles humidity to 70%, making it suitable for indoor climate-controlled spaces and outdoor installations. However, the host camera housing must provide the required environmental protection (IP66, IP67, etc.).
Q: What is the difference between IR-corrected optics and IR illumination?
A: IR-corrected optics optimize the lens's optical path for both visible light and infrared wavelengths (850nm), ensuring sharp focus and accurate color in daylight and clear imagery in IR-illuminated scenes. The camera itself must have built-in IR LEDs or external IR illuminators to actually light the scene at night.
Q: Does the SLA-T-M940DN include a CS-to-M12 adapter?
A: No. Adapters are not included. Verify mount compatibility before purchasing to avoid installation delays.
Q: What is the minimum light level this lens can capture?
A: The SLA-T-M940DN itself does not have an independent minimum illumination rating. The minimum illumination depends on the paired camera sensor. Refer to your camera's specifications for lux ratings (e.g., '0.01 lux @ F/1.6'). The F/1.5 aperture maximizes light transmission, supporting lower-light operation when paired with a sensitive sensor.
Marty AllisonPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
The SLA-T-M940DN is a solid lens choice if you're upgrading a legacy surveillance install to 12MP resolution and need automatic iris control without field adjustments. The F/1.5 aperture and IR correction handle day-to-night transitions smoothly, which matters on unattended perimeter cameras where you can't send a technician to tweak iris rings. The 9-40mm varifocal range is broad enough for both wide coverage and detail work in a single deployment—useful when you're constrained to limited camera locations or want to avoid lens inventory.
Technical Highlights:
- F/1.5 Maximum Aperture: Among the widest in the consumer surveillance lens market; maximizes light transmission to the sensor, extending usable low-light performance and supporting infrared-illuminated night operation without additional external lighting.
- 9-40mm Focal Range: Approximately 4.4x zoom; covers scenes from 77° horizontal (9mm) to ~19° (40mm), allowing single-camera coverage of entry points and perimeter sweeps without repositioning.
- IR Correction (850nm Optimized): Eliminates color-shift artifacts in IR mode; ensures that IR-illuminated scenes remain sharp at the same focal plane as daylight scenes—no refocus hunting between day and night operation.
- DC Auto-Iris, Automatic Adjustment: Responds to ambient light in real time; prevents blown-out highlights during sun glare and maintains usable signal in rapid cloud cover transitions—reduces alert noise from exposure flicker.
- CS Mount, 1/3" to 1/2.5" Compatibility: Fits most modular surveillance camera bodies; verify sensor size before procurement—vignetting occurs if lens is mounted on oversized sensors.
Deployment Considerations:
- DC Power Requirement: The auto-iris draws 12V DC from the camera or a power injector. If your camera architecture does not support DC-lens power, you'll need to source a lens power controller—adds cost and complexity to the install.
- Minimum Focal Distance of 2.5m: You cannot focus closer than 2.5 meters (8.2 feet). For tight entry-door monitoring or very close detail work, a macro lens or secondary fixed wide-angle may be necessary.
- Temperature Performance: Rated to -20°C; optical elements may develop internal fogging in rapid temperature swings or if the lens is moved from a heated building directly into sub-zero outdoor air. Allow acclimation time in extreme cold climates.
Best fit: outdoor perimeter fencing, loading docks, and retail surveillance where you need one lens to cover both wide scenes and detail work, with zero manual iris adjustment. If your budget is tight and you can live with a fixed focal length, a fixed 3.6mm or 8mm lens will cost less. If you need macro focusing or extreme wide angles, look elsewhere.
