For persistent grime, slightly dampen the cloth with distilled water.
Don’t skip this step.
If you don’t remove the grit first, you could scratch the lens when using the cloth.
The interchangeable DSLR lens has two glass surfaces that are exposed to the elements.
Be sure to clean both the front and the back elements of the lens.
You should see it when you remove the lens and look inside the body.
Just below the mirror is the focusing screen.
Clean both with a lens brush, taking care not to brush dirt into the camera.
These components are delicate, so clean them with care.
If you’re nervous about damaging them, hire a camera shop to clean them.
Some cameras have a built-in image sensor cleaning system, usually involving a fast vibration of the sensor.
Your microfiber cleaning cloth comes in handy once more for this task.
If necessary, dampen it slightly but don’t use any cleaners or solvents; these can cause peeling.
Use as little pressure as possible.
Head to a camera repair center for a professional cleaning.