23fbaf81_ess___Photographically_Curious__Mirrorless
[Overall] Shooting noise [SLR] Not very loud but still audible, due to mirror slap and shutter actuation. Older lenses with mechanical AF cause additional noises while focusing. [Mirrorless] 
Very quiet as noise is caused only by the shutter. Bodies with electronic shutters are completely silent. Virtually all lenses zoom and focus without audible noises.
SLR vs. Mirrorless | Photographically Curious
Mirrorless