newtonian focal plane

Does the eyepiece on a newtonian scope normally focus on the contracting focal plane (ahead of focus) or on the expanding focal plane (behind focus)?

Thanks in advance

Expanding, or outside the focal point. I think as a rule the distance from the center of the primary to the optical center of the eyepiece is supposed to be the sum of their focal lengths.

When an eyepiece is in focus, the field stop of the eyepiece is at the focal plane of the mirror (at least in the center of the field).