Thanks Nick. You were able to better explain this than myself,
Nick explained a formal method of star testing. There's a couple of empirical ways of testing.
The basis of this is one thing that Nick told me: "When all the photons go where they should go, then seeing conditions have less of a deleterious effect".
So when comparing two scopes, and seeing is less than perfect, these conditions are great for comparing the relative optical quality of the two scopes. The instrument with the better optics will be less affected by the poor seeing than the poorer set.
Stands to reason as with the poorer optics, photons are less well controlled, so the image will be more easily disrupted.
Another informal way of star testing can be done with splitting double stars. If you look at the second picture in post No. 10, you will see that splitting double stars does not require a full separation.
One last empirical test is done by pushing the optics to its limits with attempting to resolve the finest details possible. This is the reason behind the two challenges. The Encke Division has an angular size that is much smaller than the "theoretical" limit of many scopes 7" and larger. There are many 8" scopes that cannot resolve the Encke Division. The lunar crater resolution is more tricky as it requires the individual to compare the scope's image with images from a very detailed atlas, such as Virtual Moon Atlas. An atlas such as by Antonin Rukl is not detailed enough for this purpose.