Technical aspects of flash photography are not a trivial subject — certainly, more factors are involved than in photography under ambient light. Therefore I'm facing a tough task here, trying to present the related information relevant to the particular camera model, but also to provide at least some general background on flash photography, without which the camera-specific information would be misleading or unclear.

I'm not, however, afraid to undertake this task: whatever I do here, as bad as this article may turn out, it cannot be worse than the related section of the Olympus' own Advanced User Manual. At least I am safe here.

In any case, if you came here in a search for instant gratification ("just tell me how to ... and do not bother me with all the details"), then you found a wrong place. Try finding one of those articles which promise you "professional results withoud a need to learn", and good luck. The persistent crowd stays.

The basics: how does flash work

An electronic flash is actually similar to a controlled spark: a high voltage (at least a few hundred volts) causes a discharge in a sealed glass tube filled with an inert gas.

The camera's battery is capable of providing neither a voltage or the current needed for the discharge, therefore some electronic trickery must be applied. As a bottom line, the voltage of 7 V or so provided by the battery is converted to a few hundred volt, which is used to charge a large capacitor over a number of seconds. Only then is that charge allowed to be discharged in the tube. (In most designs there actually is yet another capacitor, storing less charge but at a higher voltage; that is used to initiate the discharge by ionizing the gas in the tube - but this is a technicality, not important in understanding how things work.)

The discharging process (and hence the impuls of light) lasts very short — usually about 1/1000 of a second or even less. And this is what makes flash light so much diferent than daylight: the duration.

The total exposure will be a sum of that provided by the flash and by the ambient light. The latter is not as intense as a burst of flash, but it is continuous, and therefore it works over the whole time the shutter is open. Unless you are shooting in a dark room, you have to remember about those two components; we will come to that later.

The shutter

Shutters used in cameras (digital or film) can be divided in two types: central (in-lens) and focal-plane. Most of digital SLRs (with the sole exception of the defunct E-10/E-20 models by Olympus) use the latter type.

Further reading

General information of electronic flashes by Thomas Tamm from Finland.