Canon Powershot A590 IS User Manual page 172

170
Do not operate the flash with dirt, dust or other items stuck to
the surface of the flash.
Be careful not to cover the flash with your fingers or clothing
when shooting.
The flash may be damaged and emit smoke or noise. The resulting
heat build-up could damage the flash.
Do not touch the surface of the flash after taking several
pictures in rapid succession.
Doing so could result in burns.
Flash