Sony a7CR Help Manual page 328

When using an external flash that is set to manual flash mode.
Note
The FEL lock cannot be set when a flash is not attached.
If a flash that does not support the FEL lock is attached, an error message is displayed.
When both AE and FEL lock are fixed, (AE Lock/FEL Lock) icon lights up.
Related Topic
Assigning frequently used functions to buttons and dials (Custom Key/Dial Set.)
TP1001159246
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