Enabling errors.log file

I've upgraded a dev site from 1.5.3 to 2.1.4. I've followed the directions for enabling the log file by

1. editing config.ini to set the value to true
2. setting permissions appropriately for application/logs/errors.log (owned by the apache user writable by the user and group)

So I think I have everything configured correctly. But I'm wondering what exactly will get logged to this. We have a theme designed for 1.5.3 that generates an error to the browser when enabled. But nothing is getting written to the errors.log file. So I'm wondering if I don't quite have the logging configured correctly. Or maybe I'm misguided into thinking the log file will capture PHP errors (which I do have set to be on in the .htaccess file) and traces within the log file.

Could anyone tell me what sort of errors or issues would be captured in the log file?

Thanks,
Jack

The log captures "Omeka" errors. Those are the types of things that get you a "Omeka has encountered an error" page.

PHP-level errors like syntax errors or calls to nonexistent functions will go to the PHP error log, wherever PHP is configured to log those things. That often means the Apache error log.

Thank you.