There is no automatic paper detection system in Tray 1.
Tray 1 is set up in the factory for A4 LEF (EU, AA) or LT LEF (NA).
However, if requested by the user, the service technician can change the paper size of Tray 1 with SP5-181 (Size Adjust).
0: A4 LEF
1: LT LEF
2: B5 LEF
3: A5 LEF