cleaning mode in NEX 7

The day before yesterday I was checking if there is any dust on the camera sensor and surprised by the dust amount there.I tried to the cleaning mode more than once and nothing was removed.then I tried to clean the sensor by a cotton swab(I dont have a rocket blower) and it worked well for me.

so what is the use of the cleaning mode ?



before and after cleaning mode

afrer using the cotton swab

thanks for looking and comments.