Quote Originally Posted by newcan1 View Post
2. The point of focus in the split screen focusing aid in the center of the ground glass focusing screen must coincide with the best focus on the ground glass screen, absent manufacturing defect; the split screen prisms are embedded in the focusing screen.
Yes, the point of optimal focus must agree between the GG image and the split prism. That's how they're designed and built.

Quote Originally Posted by newcan1 View Post
Curiously, I performed the same test on three different Nikkormats, with similar results. I also practiced with a D70 (sorry) with power off, then switched power on - each time the in-focus light was on, indicating that my focusing was accurate.
The "in focus" light just means that the image was focused within the acceptance limits defined by the system,
which means not terribly precise.

Quote Originally Posted by newcan1 View Post
But at this point I'm guessing that the problem is operator error.
I'm afraid I must concur.

I repaired Nikons for several years, and never encountered a focusing error on any that were not obviously damaged.
In fact, I've never seen a focus problem on an undamaged Nikon in the 50+ years I've been shooting them.

The probability of finding the same problem on three different cameras, all of which belong to the same shooter, are zero.

- Leigh