On an autofocus 35mm SLR like the Pentax MZ-50, the frame counter usually reflects film advance, not just shutter presses. If the counter increases when power is switched on or off, the camera may be triggering its motor/transport cycle, or there may be a fault in the film transport or electronics.

What matters is whether the film is physically moving. With film loaded, watch the rewind knob or listen for the motor drive when the count changes. If the film is advancing without an exposure, you really are losing frames. If the counter changes but the film does not move, the counter/electronics may simply be misreporting.

Possible causes include:

• a film transport problem
• an electrical/control fault
• incorrect film loading causing the camera to think it needs to advance

Try loading a test roll carefully and observe whether the take-up spool and rewind side move normally. If the camera advances film on power changes, it likely needs service. If you have no film loaded and the counter still increments, that strongly suggests an electronic fault rather than normal operation.