Hi again Simon,
Back from the wild landscapes universe so I'm reminding myself how I have the R5 set up for birds, based on several sources plus my own thoughts. It varies a bit from Glenn's. In use, for most shooting I use the custom settings C1, C2 and C3, and the 'base' AF setup in menu AF1 (which becomes customised in actual use) is as follows:
AF operation: Servo AF
AF method: 1 point AF (in C1), 4 point expansion (C2), 9 point expansion (C3)
Subject to detect: Animals
Eye detection: disable (this may seem strange, but see further below)
Continuous AF: disable
In addtion to the above, I have two back-button focus methods allocated on different buttons. The AF-ON button is set to activate whichever 'base' AF method applies depending on whether I have C1, C2 or C3 set. The * button is set to activate Eye Detection, and if pressed will immediately over-ride whatever other AF method is in use. So, I can get an initial lock on a bird by using back focus with the AF-ON button, then immediately switch to Eye Detection with the * button which is just to the right on the back of the camera.
All of C1, C2 and C3 are set to manual exposure. Controls are set as follows:
Shutter speed: the wheel behind the shutter button
ISO: The large back wheel around the SET button
Aperture: As this is the most seldom used, I have this set only to the Control Ring on the lens (or on the Control Ring Adaptor if that is being used with an EF lens).
The ring around the MODE button I have set to change the AF method, if a subject appears which requires a quick change in that.
I also have some differences in CASE settings between C1, C2 and C3 depending on their nominally intended uses:
C1 (perched or less active subjects):
Case 1 set, but with one step of left adustment on Tracking Sensitivity and Accel/decel tracking.
Nominal SS/ISO/aperture settings 1/1250, ISO 1250
C2 (general BIF)
Case 2 with default settings
Nominal SS/ISO/aperture settings 1/3200, ISO 2500
C3 (for suddenly appearing fast BIF subjects):
Case 3 with default settings
Nominal SS/ISO/aperture settings 1/3200, ISO 2500
I also have all three C1-C2-C3 set to instantly update if any setting within them is changed, hence customising on the fly depending on conditions on the day.
I think that's about it. I'm still in the process of getting used to this in practice, and it will no doubt evolve further. I can say that the R5 is a big step forward from the 5D!V I previously used for birds.
Cheers, David