I recommend Prof. Petr Beckmann’s explanation of stellar aberration in section 1.3 of his book “Einstein Plus Two” (attached).
He derives the change of the direction of the wave fronts of EM radiation from a star occurs at the outer boundary of the local-ether halo that envelops a celestial body.
For the Earth, the radius of the halo’s outer boundary is roughly 1,000,000 km where the gravitational influence of the Sun becomes dominant.
This, of course, makes moot any questions about whether the aberration occurs within a telescope.
Also, Prof. Beckmann quantitatively derives the general formula for the aberration for two transparent, non-refractive “blobs” where one is smaller than the other and is entrained within it. Aberration occurs at the outer boundary of the entrained blob as it moves within the larger one. See his short article in Volume 1, page 33 of a journal called “Galilean Electrodynamics” (GED): “Entrainment by Non-Refractive Media”:
I also recommend Prof. Howard Hayden’s article on stellar aberration in Volume 4, pages 89-92 of GED. He shows that Einstein’s explanation for stellar aberration based on Special Relativity leads to wildly incorrect predictions of the aberration of many binary star systems. See
I also recommend Prof. Howard Hayden’s paper which shows that the 1979 Brillet-Hall experiment detected the Earth’s rotation with a Michelson-Morley type experiment:
Regards,
Jim Marsen