Athlon Optics Cronus ATS Pro 35CL-400 Clip-On Thermal

The Athlon Optics Cronus ATS Pro 35CL-400 is a clip-on thermal with a built-in laser rangefinder that mounts in front of your existing daytime scope — adding thermal imaging, ranging, ballistic holdovers, and video recording without removing your optic or changing your zero. At 16.5 ounces and 5.2 inches long, it delivers the same ≤25mK sensor sensitivity and 1,600-yard laser rangefinder found in the higher-resolution 35CL-640 at a lower price point.

Key Features

• 400 x 300 Thermal Sensor with ≤25mK NETD – The 12μm pixel pitch sensor delivers the same ≤25mK sensitivity as the higher-resolution 35CL-640 — twice the sensitivity of the ≤50mK sensors in most competitors. The 400x300 resolution provides clear target identification at typical predator and varmint engagement distances.

• Built-In Laser Rangefinder (10–1,600 Yards) – The integrated laser provides ±1 yard accuracy from 10 to 1,600 yards in single-ranging or continuous-ranging modes. Range data feeds directly into the ballistic calculator for real-time holdover solutions — no switching between devices.

• Clip-On Design with QD Picatinny Mount – Mounts in front of your existing scope using the included quick-detach Picatinny adapter. Optional scope adapter rings (40mm, 50mm, 56mm sold separately) clip directly to your objective bell. Either way, your daytime zero stays intact — the clip-on adds thermal imaging without touching your scope.

• 35mm F1.0 Lens with 7.8° x 5.9° FOV – The fast F1.0 germanium lens maximizes infrared throughput to the sensor. The 7.8° x 5.9° field of view provides focused scanning coverage for target acquisition.

• 1200 x 900 OLED Display – The 0.39” OLED produces a sharp, high-contrast thermal image at 1200 x 900 resolution. At 1x digital magnification, the thermal image maps directly to your scope’s field of view — your scope’s magnification becomes the system magnification.

• Ballistic Calculator with Real-Time Holdovers – Create ballistic profiles in the Athlon Ballistics App, upload them via WiFi, and the unit calculates MOA or MIL holdovers based on live laser range data. The holdover displays directly on-screen — no dialing turrets, no mental math.

• One-Shot Zero with 5 Profiles – Zero the thermal overlay to your scope at distances from 50 to 500 yards. Five independent profiles (A–E) store different zeroing configurations for different rifles, loads, or engagement distances. A built-in leveling tool helps align the clip-on to your scope during installation.

• 7 Color Palettes – White Hot, Black Hot, Red Hot, Green Hot, Iron Red, Blue Hot, and Sepia.

• Auto-Shot Recording + 32GB Storage – Recoil-activated recording captures 3 seconds before and ~7 seconds after every shot automatically. 32GB built-in storage holds hours of footage. Manual recording and snapshots also available, with audio capture via the built-in microphone.

• 5.5+ Hour Battery + USB-C Backup – One rechargeable 18650 battery provides ≥5.5 hours of runtime — the longest battery life in the Cronus clip-on lineup. USB-C power supply keeps the unit running when the battery is depleted. Eco Mode reduces OLED brightness to 20% for extended sessions. Two batteries and a charging stand are included.

• IP68 Weatherproof, -4°F to 122°F – Fully sealed and submersible (IP68), fog-proof, shockproof. Handles high-caliber recoil and harsh field conditions.

Who It’s For

• Hunters who want thermal clip-on capability with a built-in rangefinder at the best value in the Cronus lineup. The 35CL-400 delivers the same ≤25mK sensor sensitivity, 1,600-yard LRF, and ballistic calculator as the 35CL-640 at a lower investment.

• Predator and varmint hunters working at typical engagement distances where the 400x300 sensor resolution covers the identification requirements. The 1,950-yard detection range and ≤25mK NETD handle the distances most coyote, hog, and varmint shots happen at.

• Hunters running multiple rifles who want one thermal device that moves between platforms. The QD Picatinny mount removes and reattaches in seconds, and five zeroing profiles store configurations for different setups.

• Shooters adding their first thermal clip-on who want rangefinding and ballistic holdovers without the higher investment of the 640x512 platform. The 35CL-400 is the entry point to the Cronus LRF clip-on ecosystem.