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If you have intrusive dots on your images and it’s annoying or it’s an effort to edit out the dots this is time to get the filter cleaned.
Most dots will show up in a low contrast image.
To test the camera for dust take a picture of a white wall or a blue sky. If there is dust on the filter it will show up with less contrast images and a small aperture
Small aperture, stop down the lens to the highest number on the aperture ring ie: F22.
Before clean After clean