What is the flash range of the built-in flash and are there any usage warnings?

The built-in flash has a guide number of 13 (ISO 100, in meters) and covers a 28mm lens angle. When using the built-in flash, stay at least 1 meter/3.3 feet away from the subject, otherwise part of the photo will look dark. You should also detach any lens hood when using the built-in flash, as it will partially obstruct the flash coverage. (Page 45, 51)