How is it at resolving license plates at night (via ir led's)?

The answer is, it is not a matter of day or night, the issue is a matter of resolution; even though this camera is "Ultra HD", the wide field-of-view comes in to play, and makes it impossible to read plates beyond a certain distance. The good news is that there is a formula to calculate whether a camera can read a license plate at a given distance. For that the magic number that you need to know is that you supposedly need at least 40 Pixels Per Foot (PPF) of resolution to read a plate. To determine the PPF, you divide the horizontal camera resolution in pixels by the Field Of View (FOV) in feet at the distance from the camera where you want to read the plate. A description of how to calculate this for any camera follows, but for those who want to skip ahead to the answer, the answer is, for this particular ReoLink camera, you would only be able to read a license plate if the plate was less than 50 feet from the camera, and the vehicle was stopped or moving fairly slowly. Also while the illumination is actually a separate issue, at less than 50 feet and under those conditions, the IR illuminators included with the camera would also probably be sufficient on an otherwise clear night. However a vehicle moving too quickly, or in fog or rain etc., may be unreadable. For more in-depth information and suggested alternatives, read on: For this camera, even though it's Ultra HD and therefore 3840 pixels in horizontal resolution, the FOV is fairly wide at 87.5 degrees, and this 87.5 degrees is essentially a fixed number, because the camera "zoom" is purely a digital zoom (as opposed to an optical zoom); when you "zoom in" with digital zoom, the camera is essentially faking it by just replicating the same pixels; the optical or true FOV remains unchanged. Given the fixed 87.5 degree horizontal FOV for this camera, you have to do some math to convert the horizontal FOV angle at the camera lens into the number of horizontal feet that are visible at some given distance away, but this can be done using a right triangle formula and then doubling one leg etc; there are some right-triangle calculators online. However as an example, at 50 feet from the camera an 87.5 degree FOV would translate to 96 feet of horizontal view, at 75 feet from the camera an 87.5 degree FOV would translate to 144 feet of horizontal view. Given these numbers, dividing the 3840 pixel horizontal camera resolution by 96 ft and 144 ft respectively yields ratios of 40 PPF at 50 feet and 26 PPF at 75 feet. Which means, this ReoLink camera should, in theory, be able to read a license plate at a 50 feet or less from the lens. Now this also really presumes the vehicle is standing still. Some additional caveats are, this camera has a frame rate of 20 fps. If a car is moving above a certain speed, you’re not going to be able to get a clear enough picture to grab a plate, it will be blurry. Also, in terms of seeing anything at night, that is an entirely different matter; the illuminators provided with these cameras can supposedly reach out to 100 feet, but if you find them to be insufficient, there are supplemental IR illuminators available. However your camera needs to have enough resolution to read plates during the day as previously discussed, or no amount of IR illumination will help at night. Also note the 850 nm IR LEDs can be seen as a red glow by anyone looking directly at the camera or illuminator. Lastly, if you need to read a plate at a distance greater than 50 feet, you may want to look at Ultra HD cameras that offer optical zoom, and thus a tighter FOV. We are looking at one made by Lorex (LNB9272S), but these are expensive and may not work with the ReoLink NVR, ONVIF compliance notwithstanding. For example, there may be no way to get the optical zoom to work if mixing a Lorex camera with ReoLink NVR. Hope that helps, and sorry for all the math.

Night Vision	Night Color
Night Vision Range	100 Feet
Video Capture Format	H.265
Number of Channels	8
Connectivity Protocol	Ethernet
Wireless Technology	Wired
Connectivity Technology	Wired
Unit Count	1 Count
Item Weight	0.57 Kilograms
Item Dimensions	5.51 x 5.51 x 5.51 inches
Focus Type	Auto Focus
Viewing Angle	87 Degrees
Are Batteries Required	No
Voltage	5 Volts
Power Source	Power over Ethernet
Effective Video Resolution	8 MP
Frame Rate	25 frames_per_second
Video Capture Resolution	4k
Material Type	Metal Aluminum
Shape	Dome
Alert Type	Motion Only
Waterproof Rating	IP66
Photo Sensor Resolution	8 MP
Control Method	App
Light Source Type	Infrared
Effective Still Resolution	8 MP
Color	White
Form Factor	Turret
Installation Method	Screw In
Additional Features	H.264
Indoor Outdoor Usage	Outdoor
Compatible Devices	Smartphone
Controller Type	Android
Mounting Type	Ceiling Mount

REOLINK 4K Wired Security Camera Outdoor System, IP PoE Dome Surveillance Camera with Human/Vehicle Detection, 100Ft 8MP IR Night Vision, Work with Smart Home, Timelapse, Up to 512GB SD Card, RLC-820A

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