Panasonic Lumix S5 Mirrorless Camera - Manual (Page 91)

4. Image Recording
91
Refresh the folder number to reset the file number to 0001.
¨ [ ] ¨ [ ] ¨ Select [File Number Reset]
Settings: [Card Slot 1]/[Card Slot 2]
[File Number Reset]
0 When the folder number reaches 999, the file number cannot be reset.
We recommend backing up your data and formatting the card.
0 To reset the folder number to 100:
1 Perform [Card Format] to format the card. ( l 48 )
2 Perform [File Number Reset] to reset the file number.
3 Select [Yes] on the folder number reset screen.