RedEye is a calculator that works out Depth of field (DoF)

Enter the Focal length of your lens, the current lens apature, and the focal distance.
RedEye will provide you with the Hyperfocal length, Far Focus Limit, Near Focus Limit and the intermediary working distances.

RedEye has three presets with differenct Circle of Confusion settings (CoC):
16mm (CoC 0.0125), 35mm (CoC 0.029) and RED (CoC 0.02)

Because CoC is a matter of personal preference (as it relies on intended display size, actual sensor size, and sensor/film resolution) can add a custom CoC by going to “More Settings”, turning on the custom CoC switch, and entering your CoC value.

Similarly if your lenses were designed for another sensor size than the camera you are using them on (i.e Nikon lenses on a RED) you can add a custom Lens Magnification Factor (LMF) in “More Settings” too.
A Nikon lens LMF on RED is around 1.52.