Describe the bug

I'm just setting up a photo booth, using a Canon EOS 450D. I noticed that, during initialization, the camera focuses and takes a picture. If focusing fails, the software reports an error message and allows to retry the operation.

The same is true if focusing fails during taking a picture - it gives the option to retry. Wouldn't it make sense to automatically retry the operation, say, three times and only report the error message if it fails three times in a row?

I've been experimenting with the various gphoto2 backends, the most reliable is, currently, the python-gphoto2 backend.

To Reproduce

Steps to reproduce the behavior:

1. Start Photobooth
2. Prevent focusing during startup, for instance with the lens cap on
3. See error message

Expected behavior

See above, retry focusing.

Hardware

• Raspberry Pi 3B
• Canon EOS 450D
• GPIO: No
• 7" Raspberry Pi Official Touchscreen

Software (please complete the following information)

• Raspbian Buster
• Python 3.7.3