Mick wrote:

At present Mars should be over 1/2 degree at 100 X's, which is a full moon
disc. At 200 X's, Mars should appear
as the moon would at 100 X's.

Surely you mean "At 200 X's, Mars should appear as the moon would at 2 X's."
Check your math.

This just doesnt happen because the moon
takes up the whole field in the EP at 100X's

So there is some optical trick occuring that eludes me...