You just have to deal them in post processing. It really is not practical and in some ways possible to keep your camera sensor clean all of the time, regardless of brand of camera.
Each time you change the lens, no matter how careful you are, dust and other alien particles will get in there and land on your mirror and especially the electrically charged image sensor. Turning the camera to the off position before changing lenses can reduce this but will never eliminate it.
I took this image with my old and very much used D3200, when the image sensor was as it’s dirtiest.
The image was shot at f/16 with a 13 second shutter speed at ISO 100, to purposely show the dirt as best I could. I never got round to sharing this demonstration image until now.
After using the healing tool in Adobe Lightroom# all the spots were fairly quickly and easily removed.
I thought I would share this for all to see in case anyone thought lens spots were not normal and to show the need for basic post production using software.
© Tim Hill