eruvin 50

from far away, 2000 cubits, under the tree could be quite specific.

but as get closer, that area gets blurred and loses definition.

(naming a specific landmark 2000 cubits away allows one establish residency there, walk there. and from that landmark walk a further 2000 cubits home. but saying under a tree is too vague, as it probably bigger than 4 cubits. has to be a specific point. in the drawing the red under the tree is diluted as the scale is bigger)