First clean the front of the camera lens to make sure the issue is not being caused by dust, dirt, spots, or watermarks.
This also can occur when using a high ISO setting. It is typically more visible when shooting in dark or poorly illuminated areas. Whether the ISO is set manually or automatically by the camera, high ISO settings make the image sensor more sensitive to light. However, while the image sensor becomes more sensitive to light, high ISO settings also make pictures more susceptible to picture noise. This is normal with digital photography; film cameras can encounter the same thing when using faster speed film.
The following are a couple of recommendations to reduce this issue:
- If using the automatic setting on the camera, make sure you are shooting in a well-lit environment if possible.
- When using manual settings, lowering the ISO setting and using the flash is suggested - providing your subject is not too far away.