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In that experiment, based on the data, the ED80 was resolving 53 line/mm at the retina and the stopped down 9.25 was resolving 75 lines/mm based on an f/34 optical train for the 80 and an f/24 optical train for the SCT.

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Hmh...wonder where do these numbers come from?
Eye can only see what is resolved in the focal plane
of the objective. Conventional MTF gives linear cutoff
frequency as 1/LambdaF, which for 0.00055mm Lambda comes
to 1818/F lines per mm (F being the system F#). That
gives 242 lpmm to an f/7.5 system (80mm ED), and 61 lpmm
for an f/30 (approx. C9.25 masked down to 80mm). Sure,
angular resolution is the same.

That is for bright, contrasty lines. For low-contrast lines,
number of lines resolvable will be only about half as many.
Any other factor lowering image contrast will have it further reduced.

Vlad

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Vlad that is the resolving power of the image at the retina, not at the image plane. That would also be a maximum because I was not adding the combined resolving powers of the componants of the scope/EP/eye, but it illustrates approximately the difference in resolving power between the two setups.

And you are right about target contrast, but this was just to illustrate a theoritical maximum to show that focal length was not a determining factor in the comparison as the systems should be producing fairly similar images. The fact that the SCT was not performing very well means that there was something up with the optics.

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