Sony ILCA-99M2 - Manual (Page 366)

MENU
→
(Setup)
→ [Cleaning Mode] → [Enter].
The image sensor vibrates a little to shake off the dust.
2
Turn off the product following the instructions on the screen. 3
Detach the lens. 4
Push the mirror lock lever (A) and open the mirror. 5
Use the blower to clean the image sensor surface and the surrounding area. 6
After you finish cleaning the image sensor, push down the mirror until it clicks.
Push down either side (B) of the mirror.
7