If you set c3: Stand-by timer to "No Limit", the camera will not go to sleep and you'll be able to react instantly. I did an experiment. If you chose the 'Prioritize Viewfinder' mode then the camera will run for almost 3 hours before it shuts down by itself (overheating?). The remaining battery is at 25%. I have not tried it with IBIS off.
I did an experiment. If you chose the 'Prioritize Viewfinder' mode then the camera will run for almost 3 hours before it shuts down by itself (overheating?). The remaining battery is at 25%. I have not tried it with IBIS off.