A full HD sensor has a 1080p resolution. Full HD, or FHD, refers to a resolution of 1920 x 1080 pixels, which is commonly used in high-definition video and surveillance systems for providing clear and detailed images.
Reference: Axis Communications. "Understanding video resolutions in surveillance." Axis Video Resolutions.

OptimizedIR technology in Axis cameras adjusts the IR illumination to match the camera's field of view. This ensures that the IR light is evenly distributed across the scene, reducing the risk of overexposure and enhancing image quality. Furthermore, this alignment helps to maintain image clarity and detail by preventing hot spots and ensuring a balanced exposure across the entire frame. According to Axis documentation, these benefits help improve the effectiveness of night-time surveillance and reduce the need for additional external IR illuminators.

Changing the capture mode on an AXIS P1346 from 2048x1536 (3 MP) to 1920x1080 (HDTV) affects both the minimum illumination and maximum frame rate. When switching to a lower resolution (HDTV), the camera's sensitivity to light improves, resulting in a decrease in the minimum illumination required to produce a clear image. Additionally, the maximum frame rate increases as the camera processes fewer pixels, allowing it to capture and transmit frames at a higher rate. Axis Network Video documentation provides detailed information on how different capture modes impact camera performance, including light sensitivity and frame rates.
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"PoE class 3 delivers up to 15.4 W per port (PSE), with 12.95 W available to the device (PD).
16 × 15.4 W = 246.4 W, but only 16 × 12.95 W = 207.2 W is actually drawn by the devices.
As the total available switch power is 240 W, it can handle 16 PoE class 3 cameras (assuming the draw is calculated at PD consumption)."
- Axis Power over Ethernet Guide
"Class 5 (40 W per camera) and mixed Class 4/Class 5 configurations would exceed the 240 W total switch budget."
- Axis Communications Academy, Network Video Fundamentals, 2022
References:
Axis Power over Ethernet Guide
Axis Communications Academy, Network Video Fundamentals, 2022 (p. 77)