9. The flash is charged by lightly pressing the camera exposure button. The exposure mode is electronically inhibited until the flash is fully charged. When the green LED comes on, a picture can be taken by pressing the exposure button in all the way.

10. An alternate way to charge the flash is to lightly press the exposure button. The button can then be released. After the green LED has come on the flash will stay fully charged for approximately one minute. When the exposure is ready to be made, the exposure button is pressed in fully, in one motion.

11. The built-in flash is an electronic quench-type flash. It can provide a full output of about 340 zonal-lumen seconds (ZLS) to illuminate a scene or it can be shut down early to provide less light to the scene. The way the camera decides to provide full or partial light output will be discussed later.

FLASHTUBE

12. Whether or not the flash provides full output, the main capacitor delivers the same amount of energy. Therefore, if the flash is ordered to shut down early, some means must be found to dissipate the remaining energy in the circuit. This remaining energy is diverted through a thyristor (TH1) on the strobe board.

13. Now, lets talk about the way the camera logic decides when to fire the flash and how much light it needs from the flash before it quenches it.

14. Refer to the Sequence of Operation section for a description of the order in which all of the events in an exposure cycle occur. (The operating sequence is also shown in diagram form, at the end of Section 2.)