Here’s an interesting post and thread from CN
https://www.cloudynights.com/topic/7...magnification/
I’m of the opinion it’s almost impossible to make an accurate assessment and comparison based on one formula or calculation as there are no standard or familiarity frames of reference between the two.
The human eye looking through an eye piece and digital camera sensor are incomparable in regards to physics and mathematics.
Probably an ongoing topic , hotly debated I suspect