Viewfinder Dust

[Dusty]

You're blowing the dust off of the sensor and into the sensor box, where it's getting on the mirror or underside of the viewfinder screen. After the sensor cleaning, blow off the mirror and viewfinder screen.

It also helps to hold the camera lens mount down when cleaning so that the dust drops out.

Dusty

[Dusty]

After the sensor cleaning, blow off the mirror and viewfinder screen.
Dusty

I didn’t know you could blow off the viewfinder dust while in cleaning mode.

Not in Cleaning Mode! Simply remove the lens, point the mount down and use the blower on the mirror box and underside of the viewfinder.

Dusty