Mamiya 7 II Instructions Manual page 25

When on manual, 10 seconds after activation, the LED indicators will go out, to save battery
power. If they do so during metering, press the Shutter Release Button half way again.
Please note: The LED indicators will disappear 10 seconds after you remove your finger from
the shutter release button in the following situations:
1) When the film advance lever is not advanced.
2) When the light shield curtain is closed.
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Taking Photographs