When is a photo “correctly” exposed? As a rule of thumb we can say that a photo is correctly exposed when light and shadow areas still demonstrate detail. And thus if you want to illuminate a subject with flash, you have to make sure that the respective flash power of the individual light sources is adapted to the exposure parameter settings you’ve selected at your camera. Otherwise, parts of the photo may be over or underexposed.
Read more about this issue in an excerpt from a book published by Rheinwerk Verlag.
Modern cameras take care of exposure metering themselves in the subject and automatic modes, and deliver satisfactory results – even when detachable flash units are used, insofar as the camera and the detachable flash unit can communicate with each other regarding exposure via a data protocol. In the case of external flash units there’s no TTL or E-TTL function, and the camera and the flash unit have to be adjusted manually.
Read more about this issue in an excerpt from a book published by Rheinwerk Verlag.
