REOLINK RLC-823S1 PTZ Review

Why optical zoom is different from a wider sensor

In the DORI formula, distance scales directly with tan(hfov/2), and tan(hfov/2) is sensor width divided by twice the focal length. Increasing the focal length, which is exactly what optical zoom does, shrinks tan(hfov/2) and pushes every DORI distance out proportionally. A 5x optical zoom multiplies the effective focal length by up to 5 at full telephoto, which multiplies every DORI distance, detect, observe, recognise and identify, by close to the same 5x factor relative to the widest setting.

Digital zoom does none of this. It crops and enlarges pixels that were already captured at the wide setting, so it never adds resolution at range the way a longer physical focal length does. The distinction matters most on a long driveway, where a fixed wide lens can show that a vehicle is present but never resolve a plate, no matter how much the recorded footage is digitally zoomed afterward.

What is missing to compute an absolute distance

The DORI formula needs a specific focal length in millimeters, and this listing states a zoom ratio rather than the base focal length at the widest end. That means the 5x multiplier is verifiable and real, but an absolute number like "identifies to 40 meters" cannot be honestly stated here without inventing a starting focal length this listing does not provide.

Anyone who owns this camera can get the real number by pulling the wide and telephoto focal lengths from the printed manufacturer datasheet and running both through the DORI distance calculator. Anyone comparing this camera to a fixed-lens model before buying should compare the published zoom ratio against a fixed camera published focal length only in relative terms, not by assuming a specific starting point.

Night vision and power draw, what is published and what is not

REOLINK states that infrared night vision on this camera reveals detail from a distance of up to 60 meters (about 197 feet), and that the camera also offers a full color night vision mode. That is the manufacturer own figure for this camera, and it should be read the same way any stated IR distance is read: a best-case measurement, not a guaranteed working range.

This listing does not publish a PoE power class for this camera. A motorized pan-tilt-zoom mechanism typically draws more current than a fixed bullet or dome camera of the same resolution, so budgeting this camera on a shared PoE switch on the assumption it only needs the base 802.3af 15.4 watt class 3 allocation is a real risk. Confirm the actual class from the manufacturer datasheet and run it through the PoE power budget calculator before finalizing a switch.

Is this a hands-on review

No. This is not a hands-on review. This camera has not been mounted or run through a pan-tilt-zoom cycle by anyone on this team, and no distance or power figure above comes from a measured result. Everything here is either the published listing figure or the geometric implication of the published zoom ratio.

Who should not buy this

A fixed entry point that never needs to look in more than one direction gains little from pan and zoom and pays a real premium for both; a fixed bullet or dome camera at the same 8MP resolution covers that case for less money.

Anyone budgeting a PoE switch to the tightest possible margin should be cautious here, since the actual power class is not published and a motorized head is unlikely to sit at the lowest class available.

Anyone who wants a firm, stated identify distance in meters or feet before buying will not find one for this camera without pulling the base focal length from the manufacturer datasheet themselves.