What is AE exposure lock?

The answer upstairs is really nonsense.

AE exposure lock refers to automatic exposure lock. Press and hold this button to lock the currently measured exposure data, and still expose according to the just measured data when moving the lens to change the composition. Especially effective for backlighting and surround shooting.

As for why there are no consumer-grade digital products, it is not surprising. You can't expect all the functions of Shen Da to be available in Li Xia, can you?

The only explanation for AE lock is "automatic exposure lock", which should not be called "AE lock" if it is given other functions in combination with the menu. According to the description upstairs, it should mean "automatic exposure of depth of field", abbreviated as "a-dep". I have never seen this button combined with "AE lock".