Thermal imaging and optical configuration

The Stellar 4.0 SQ50L uses a 640 × 512 VOx detector with a 12 μm pixel interval and a 50 mm F1.0 objective. Its NETD of less than 12 mK, specified at 25°C and F1.0, describes sensitivity to small temperature differences within the observed scene. A 50 Hz frame rate supports viewing moving subjects and scanning across terrain. The field of view measures 15.2 × 12.2 m at 100 m, defining the area visible when assessing a location. Rear-ring focusing provides adjustment from a minimum focusing distance of 10 m. The manufacturer specifies a detection range of 2,600 m; this is a detection figure rather than an identification distance.

Display, magnification and viewing adjustments

Magnification runs from 3.5× to 28.0×, with a dedicated digital zoom ring providing adjustment during observation. The SQ50L 4.0 utilises a 1.03-inch AMOLED display, that has a resolution of 2560 × 2560, while picture-in-picture provides an additional viewing window within the display. Six palettes allow the thermal scene to be presented in different colours, supported by brightness, contrast and warm or cold tone adjustments. These controls provide flexibility in how the image is viewed. An 8 mm exit pupil and 55 mm eye relief define the eyepiece viewing geometry. Dioptre adjustment from −5 D to 5 D allows the display to be focused to the user’s eyesight.

Range measurement, zeroing and recording

The Stellar 4.0 SQ50L laser rangefinder is incorporated into the objective lens and measures distances from 10 m to 1,200 m, with specified accuracy of ±1 m. Onboard ballistic calculation provides a separate function alongside measured distance information. Five zeroing profiles allow multiple zeroing configurations to be retained, while freeze zeroing holds the image during reticle correction. For documenting use, the scope supports snapshots, video and audio recording, including recoil-activated recording. Built-in 64 GB EMMC storage retains captured files, and the local album allows them to be reviewed on the device. Hotspot connectivity supports connection to a phone for live viewing, remote control and access to recordings.

Power, mounting and environmental specifications

The power system od the SQ50L 4.0 combines two internal rechargeable lithium batteries with a replaceable rechargeable 18650 battery. The external battery supplies power first, followed by the internal batteries. Specified continuous operating time is 9.5 hours at 25°C with the laser rangefinder switched on. USB Type-C charging replenishes the internal batteries; the external battery requires the separate charger. Standard 30 mm mounting provides the interface for scope rings. The unit weighs 1,008 g with the external battery fitted and measures 439.6 × 82.9 × 74.3 mm. Its IP67 protection rating, −30°C to 55°C operating range and specified maximum recoil of 6,000 J define its environmental and mechanical limits.