Hanwha SLA-M2890DN 3MP CS-Mount Auto Iris Varifocal Lens
Overview
The SLA-M2890DN is a precision varifocal lens purpose-built for 3MP surveillance cameras with 1/2.8" sensors. Optimized for Hanwha IP cameras, this CS-mount lens delivers consistent imagery across variable lighting conditions—from bright daylight to near-total darkness—without manual iris adjustment or recalibration between day and night operation. The F1.2 DC auto iris mechanism and IR-corrected optical design mean deployment is straightforward: mount it on a compatible 3MP camera body, adjust the focal length and focus once, and the lens handles exposure changes automatically.
Key Features
- F1.2 DC Auto Iris: Maintains optimal exposure across rapid lighting changes. The auto iris adjusts iris opening in milliseconds—critical in retail or transit environments where exterior light floods in through doors or windows. No manual intervention required; the camera delivers stable video whether it's noon or dusk.
- Varifocal 2.8–9mm Focal Range: Adjustable field of view lets you set the lens once during commissioning. 2.8mm provides wider coverage (roughly 110° HFOV on a 1/2.8" sensor); 9mm tightens to roughly 35° HFOV for targeted monitoring of entry points or restricted zones. Motorized focus is not required—manual focus adjustment is sufficient for fixed installations.
- IR-Corrected Optics: Dual-spectrum optical formula compensates for infrared wavelength shift. In day/night setups with IR illumination, the image remains sharp across both visible and near-IR spectra—no color fringing, no focus shift when night-mode IR filters engage. This eliminates the calibration headache of swapping lenses or refocusing between modes.
- CS-Mount Interface: Industry-standard mechanical coupling works with most 3MP camera bodies—check your camera's lens compatibility before ordering. CS-mount is smaller and lighter than C-mount, typical in compact surveillance housings.
- 1/2.8" Sensor Optimization: Optical formula is engineered specifically for 1/2.8" sensors, ensuring megapixel-grade sharpness edge-to-edge. Oversized lenses on small sensors introduce aberrations and vignetting; this lens is matched to the sensor size.
- Compact, Lightweight Design: Fits standard compact turret and mini-dome housings without bulk or weight penalty. Ideal for ceiling-mount or wall-mount scenarios where space or load-bearing matters.
Integration & Compatibility
Before purchasing, verify your camera body accepts CS-mount lenses and has a 1/2.8" sensor rated for 3MP (2048 x 1536 or equivalent). The SLA-M2890DN is optimized for surveillance lenses on Hanwha 3MP cameras, but also pairs with third-party 3MP bodies using the same mount and sensor format. Check the camera's lens-removal procedure—some compact housings require disassembly to access the mount.
When to Choose a Different Model
If your deployment requires higher resolution (5MP, 8MP), look for Hanwha varifocal lenses in their higher-MP families—the optical formula scales with sensor size. For fixed narrow-angle requirements (e.g., dedicated entry monitoring), a fixed 8mm or 12mm lens may reduce cost and eliminate focus drift over time. For extremely wide coverage in confined spaces, a lower-range varifocal (e.g., 2.8–6mm) might suit better. For outdoor perimeter work in harsh weather, confirm the lens housing itself meets your IP/IK rating requirement—the lens optical elements are sealed, but inspect the barrel material and coating specs in the full datasheet.
Deployment Notes
Focus adjustment is manual (twist-ring); set it during commissioning and leave it. In day/night installations, disable automatic focus on the camera side if the firmware offers it—manual lens focus is more stable. For IR-illuminated scenes, verify the camera's IR cut-off filter timing aligns with the auto iris response; poor synchronization can cause brief exposure flicker when transitioning between modes. Test focus quality at both day and night before sealing housings.
Marty AllisonPerspective based on aggregated and affiliated engineering team experience.
The SLA-M2890DN is a lens that stays out of the way. F1.2 auto iris and IR correction mean you're not debugging exposure or focus problems months after install. The varifocal range is practical—2.8–9mm covers most indoor-to-mid-range outdoor surveillance without swapping lenses or purchasing multiple models.
Technical Highlights:
- F1.2 Iris Speed: At F1.2, the lens gathers light faster than slower alternatives (F1.6 or F2.0). On a 3MP sensor in low-light scenes, this translates to less noise and better motion-blur performance before the camera's ISO sensitivity maxes out. In retail or warehouse settings with mixed fluorescent and natural light, the fast iris keeps exposure stable without forcing aggressive sensor gain.
- 2.8–9mm Range on 1/2.8" Sensor: At 2.8mm, you're looking at roughly 110° horizontal coverage—wide enough for hallways or entry vestibules. Zoom to 9mm and you're tightening to ~35°, suitable for ATM, register, or perimeter fence monitoring. One lens covers scenarios that would otherwise require two fixed-focal models; fewer SKUs to stock, simpler commissioning.
- IR Correction Without Refocus: Noncorrected lenses shift focus when IR filters toggle. IR-corrected optics eliminate that calibration dance. Image sharpness remains consistent whether the scene is backlit daylight or pitch-dark with IR fill—no service calls to re-focus in the field.
Deployment Considerations:
- Manual focus only: if your site requires motorized remote zoom/focus, this varifocal is not the answer. Pick a fixed focal length or step up to a motorized zoom lens on a PTZ camera.
- CS-mount specificity: verify your camera body is CS-mount, not C-mount. The thread pitch is different; forcing a mismatch will damage the mount. Always test-thread by hand before tightening.
Deploy the SLA-M2890DN on fixed 3MP Hanwha or compatible camera bodies in retail, warehouse, or mid-range outdoor perimeter work. The combination of fast auto iris and IR correction means you set it once and trust it. Real win for integrators who are tired of field-troubleshooting exposure creep or IR-mode focus drift.
Frequently Asked Questions
Q: Is the SLA-M2890DN motorized or manual focus?
A: Manual focus. The lens uses a twist-ring focus adjustment. Set focus during commissioning and leave it fixed. There is no motorized zoom or remote focus control on this model.
Q: Can I use the SLA-M2890DN on non-Hanwha 3MP cameras?
A: Yes, if the camera body is CS-mount with a 1/2.8" sensor rated for 3MP resolution. Always verify mechanical and optical compatibility before purchase. Some compact housings make lens removal difficult—check the camera manual.
Q: Does the auto iris work in complete darkness?
A: The auto iris responds to available light. In complete darkness without supplemental illumination, the iris opens fully (F1.2) but the camera relies entirely on IR illumination or other light sources. Pair this lens with a camera that has strong low-light sensitivity and IR capability for night operation.
Q: What is the minimum object distance (close focus)?
A: Typical for this class is 20–30cm (8–12 inches) depending on focal length setting. Check the full datasheet for exact close-focus specifications at 2.8mm and 9mm extremes.
Q: Is the lens barrel weatherproof for outdoor use?
A: The optical elements inside are sealed, but the barrel material and housing depend on the complete camera enclosure. For outdoor perimeter installations, verify that the mounted camera housing meets your required IP and IK ratings—the lens alone is not rated for direct rain or impact.
Q: How do I know if my camera is CS-mount or C-mount?
A: CS-mount and C-mount use the same thread (1 inch, 32 threads per inch) but differ in back-focal-distance by 5mm. Force-fitting a CS-mount lens onto a C-mount camera will not focus to infinity and may damage the mount. Check your camera's specification sheet or contact the manufacturer before ordering.
