What Security Camera Lens Do You Need for 50 Feet?

At 50 feet, lens choice depends on what you need to see. A wide lens can confirm that a person or car is present. Identification usually requires a much narrower view so more pixels land on the target.

Start from scene width, not millimeters

If you need to see a 60-foot-wide yard at 50 feet, a wide lens is appropriate but identification detail will be limited. If the important zone is a 12-foot gate, a longer lens can place several times more pixels on the subject.

Example with a 4K stream

At 3840 horizontal pixels, a 50-foot scene width gives about 77 PPF—near the commonly used DORI identification planning density. A 25-foot scene gives about 154 PPF. A 100-foot scene gives only about 38 PPF.

Sensor width changes focal-length requirements

A 6mm lens on a larger sensor can be wider than a 6mm lens on a smaller sensor. Use horizontal FOV from the specification sheet when possible. If only sensor width and focal length are available, calculate the angle from those values.

Use varifocal if the geometry is uncertain

For a 50-foot gate, driveway or detached building, a motorized varifocal camera can be easier to tune than guessing whether 4mm, 6mm or 8mm will produce the correct scene width.

Enter the distance, sensor width and lens in the Camera Coverage & Focal Length Calculator.