I have been experiencing a problem with dust in both A7 and A7ii cameras. This dust can appear literally between shots, and when the lens hasnt even been changed - following professional cleaning at a camera shop. ( Even he said they are a nightmare to get totally free of dust- he can clean it and by the time the lens is on it has dust again).

I use mostly the same lens almost all the time so dont change lenses often, and now only change indoors in case of a breeze. I keep my lenses clean and blow with a rocket blower prior to changing lenses. I do everything we are supposed to do on changing lenses, pointing down, keep camera switched off, avoid a dusty atmosphere, change over quickly - I dont even breath when giving the sensor a bow or dry wipe!

The dust spots are definately on sensor not lens, and most of the time can not be seen by eye. 

Im sure most people would never notice them, but I do because I work in macro all the time and shoot mostly at F18 with a clean background.  Thing is that I enter a lot of competitions and I like to get everything right in camera - one of the competitions is only straight out of camera and they do not allow removal of dustspots, so I need to get my sensors spotless.

I have noticed the blowing it with the giotto rocket blower makes it worse every single time ( yet the same blower works on my partners 3 cameras ( Nikon and one is mirrorless). A dry swab does help but I cant even get less than 20 dust spots. Note they move around all the time - so not stubborn dust stuck to the sensor.

I know Im not the only person experiencing this, I have a few friends with the same issue - but they dont shoot macro with clean backgrounds so its not as noticeable for them. I know I can shoot at a wider aperture say F8 and they are a lot less visible - but I need to shoot at F18 for my speciality.

I love my Sony mirrorless, but if I cant resolve this soon Im going to have to change and sell all my equipment.