Distance between the bottom of the focuser tube and the focal plane =
Focuser tube inside diameter =
Diagonal size (minor axis) =
Distance between the diagonal and the focal plane =
Distance between the diagonal and the focuser baffle =
Distance between the diagonal mirror and the diagonal baffle =
Primary mirror diameter =
Primary mirror focal length =
Primary mirror baffle distance in front of primary mirror =
Telescope tube inner diameter =
Here's an image showing the focuser baffle and diagonal baffle for a 20.5 inch [52cm] f4.8 reflector.
Not pictured is the primary mirror's baffle, which can be a baffle surrounding the primary mirror or an extension of the telescope tube.