[. . . ] However, it is worthwhile reading the operating instructions first to learn how to use the flash correctly. This flash unit is suited for: · analogue and digital Canon cameras (EOS and PowerShot) with TTL- , E-TTLand E-TTL-II - flash metering. Do not expose the flash unit or battery charger to dripping or splashing water such as rain! When a flash is fired, no opaque material may be in front of or directly on the reflector screen of the flash unit, nor may there be dirt on the reflector screen. [. . . ] Tip: If you do not necessarily need the full guide number and maximum flash range of the flash unit, you can leave the zoom reflector at the position for the shortest focal length of the zoom lens. This will provide full light coverage of the picture and eliminate the need to continually adjust it to the focal length of the lens. Example: You use a zoom lens with a focal length range of 35 mm to 105 mm. In this case, you set the position of the main reflector of the flash unit to 35 mm. resetting to auto-zoom · Touch the shutter release to begin a data transfer between the flash unit and the camera.  The setting must occur immediately after accessing the special functions Since otherwise the flash unit automatically switches back to normal flash operation after a few seconds! The motor zoom main reflector of the flash unit can illuminate lens angles from 24 mm (35 mm format): Thanks to the use of the integrated wide-angle diffuser , the illumination widens to 18 mm. Auto zoom The zoom position of the main reflector is automatically adjusted to the lens focal length when the flash unit is used with a camera that transmits the data related to the lens focal length. After the flash unit has been switched on, , , Zoom" and the current zoom position of the main reflector are shown in the display. If a focal length of less than 24 mm is used, , , 24" flashes in the display as a warning that the shot cannot be completely lit. If so desired, the position of the main reflector can be manually adjusted in order to achieve particular lighting effects (such as spot effect etc. With the remote slave mode activated, press the button combination , , Select" until , , CH" (= remote channel) flashes in the display. After about 5 seconds the display stops flashing and the setting is saved automatically. after activation of the remote slave mode , , , SL " appears in the display. In addition, the slave group (GROUP) selected and the remote channel (CH) are shown. Once the slave flash units are flash ready, the AF measuring beam will blink. Press the manual firing button on the master or controller flash unit to fire a test flash. The slave flash units will respond in succession, according to slave group, with a test flash. if a slave unit fails to fire a test flash , check the settings for remote channel and slave group. Correct the position of the slave flash unit so that it is able to receive light from the master flash unit.  The flash mode is transmitted automatically by master or controller. When the flash unit functions as master in the cordless remote system, the activation of the modelling light also activates the modelling light of slave flash units  The same remote channel must be set on the slave flash unit as on the A series of flash exposures FB (flash bracketing) can be carried out in the TTL flash modes ( TTL , E TTL , E TTL HSS; see 7. [. . . ] The flash capacitor built into the flash unit undergoes physical change if the unit is not switched on for a prolonged period. For this reason it is necessary to switch the unit on for approximately 10 minutes at least once every three months. The camera does not transfer data to the flash unit · There is no exchange of data between the flash unit and the camera. The aperture setting on the flash unit is not automatically adjusted to that of the lens. [. . . ]