Identification distance
Our estimate of how far away you can tell a coyote from a fox or a dog. It is calculated from the lens and sensor, assuming good conditions.
What it means
Identification is the point where you can say what the animal is, not just that something warm is there. For a coyote hunter that means telling a coyote from a fox, a bobcat or a neighbor’s dog, which is the call you need before you shoot.
How we calculate it
We use Johnson’s criteria, a long-standing rule from imaging research: identification takes about 12 pixels across the target’s smallest dimension. For a coyote that is shoulder height, about 22 inches from feet to shoulder.
The math: identification distance equals 22 inches divided by 12 times the angle one pixel covers (pixel pitch divided by focal length). We round the result to the nearest 5 yards.
A shortcut for common sensors: at 12 µm pitch, identification distance in yards is about the focal length in millimeters × 4.2. A 25 mm lens gives about 105 yards, 35 mm about 150, 50 mm about 210 and 60 mm about 255. At 17 µm, multiply by about 3.
Why shoulder height
An earlier version measured body length, which gave ranges about 60 percent longer than hunters report. Shoulder height is the smallest dimension, as Johnson’s method intends, and it lands on the common field experience of about 150 to 200 yards for confident coyote ID on typical units.
Its limits
- It assumes good heat contrast, a broadside coyote in the open, sharp focus and a steady view. Summer heat, humidity, fog, brush and a moving animal all shorten it.
- It is calculated at base magnification. On thermal, digital zoom does not extend it: the sensor has no more pixels to give.
- Twelve pixels is a 50 percent threshold in the research, not a guarantee. Some people will call the animal sooner, others later.
- For digital night vision we calculate it on the screen at base zoom, because a 4K sensor on a 1280-pixel screen shows only part of its detail until you zoom in. The spec table adds the zoomed-in, full-sensor figure. Both are detail limits in good light. At night, sensor noise and the reach of the IR illuminator usually set the real limit, often far shorter.
- Tube night vision has no pixels, so we do not calculate it there.
Compare it with the maker’s detection range, which measures something much easier.