How far away should my eyes be from the PCEye 5 when using the device or calibrating?

The optimal distance between the front of the device (when mounted on the mounting plate) and your eyes is 20-37 inches (50-95 cm).

If you are leaning sideways or are lying down:

Tilt the device in order to keep it parallel with the   eyes.

Maintain the optimal distance of 20-37 inches (50-95 cm).

Make sure the sun is not shining directly onto the screen or into your eyes.

NOTE: The optimal distance between the device and the user’s eyes depends on the size of the screen. The greater the screen size, the greater the optimal distance. Monitors that are larger than the “up to maximum screen size limitation” should not be used.