For Studio, the main log file (bdd-studio.log) contains all of the log messages.
By default the bdd-studio.log is stored in the WebLogic domain in the $BDD_DOMAIN/<serverName>/logs directory (where serverName is the name of the Managed Server in which Studio is installed).
The main logger does not print messages from the com.endeca.portal.instrumentation classes. Those messages are printed to the metrics log file.