Using Brand New R5 with Old Lenses and AF Works Occasionally

[johndd]

Bought a Canon R5 thru their upgrade program when my 5D Mark III was unrepairable. Now in New Zealand and experiencing AF failure a lot on both Canon "legacy" 70-200 2.8 and Tamron "legacy" 28-75 2.8.

Comments? I want Canon to know this in case it's an issue that requires camera to be replaced/repaired when I return in June. 

[Tronhard]

Hi John, and thanks for the update:
I'm sorry you are still having such a difficult time with this.  So, I have a couple of questions and suggestions for you, if I may...

1. What kinds of subjects are you shooting?
2. How is your autofocus set up on that camera?
3. What is your current firmware version? It should be 1.8.1
4. Have you tried doing a factory reset?  You could save your configuration to one of the C modes, do the reset and if you find no improvement with the default settings, then you can switch to your current settings very quickly.
If you do find the autofocus is improved, I would sugges applying your settings one at a time and testing the autofocus, in case some combination is causing you strife.  Not being there and privvy to the situation on the ground means I have to make suggestions you may already have considered and applied.

[Peter]

I got a lot of non-keepers after using Servo AF Case 4 for planes far away. I had changed it to Case 4 due to that I needed it at that time when taking pictures of my son running and jumping, but forgot to move it back to Case 1 or 2 for "slower" targets.

[Tronhard]

@Peter:
That is interesting and reflects the complex nature of the autofocus systems these days.  I have my focus and drive settings configured for different scenarios, and I have assigned each to one of the C1 - C3 modes, so that I just switch those and I can configure the camera specifically or go back to Av (or whatever) in a more generic configuration.  So far it has worked well for me.

[Tronhard]

For a detailed explanation of the focusing modes on the R5, I recommend watching this video from Rudy Winston.  Use the navigation bar along the bar to skip bits that are not relevant.
Canon Auto Focus Explained with Canon Technical Advisor Rudy Winston - YouTube