[74tuc]

Hi Jase,

1. Re:
"It is also impossible to evaluate the performance of any telescope with a
refracting element (Schmidt corrector, Maksutov corrector, doublet or triplet)
with the simple knowledge of the Stehl Ratio for one wavelength (usually green), "

Please tell us what you understand by "Strehl Ratio" and further why you believe
the quoted statement is true?


2. Re:
"Encircled Energy Ratio - The EER is the ratio between the
total energy inside a given angular radius from a mirror's
diffraction pattern to the total energy inside the errorless
circular aperture's diffraction pattern."

You have just given us a definition of Strehl Ratio called by a different name.

The above statement may be read as:

"Strehl Ratio - The SR is the ratio between the
total energy inside a given angular radius from a mirror's
diffraction pattern to the total energy inside the errorless
circular aperture's diffraction pattern."

where: "given angular radius" = Radius of the Airy Disc.

I leave it to you to figure out why Strehl Ratios in a system are multiplied.
When you find the answer you will discover that the first statement is not true.

Regards,

Jerry.