[Randalthorro]

Focal length and aperture literally mean nothing for this instrument (camera). Telescopes are multi instrument and it’s the telescope plus instrument specific mounting configs that determine these. (Focal length is actually pointless except to make sure you design the light path correctly).

Aperture is talked about in the light collecting area of the mirror, and often summarized to its diameter. 8m class telescope, is a telescope with an approximately 8m diameter mirror.

Hubble is a little over 1m.

Other things matter way more for a telescope and are much more interesting.