Barrie Davis wrote:
If your flashgun is like MOST modern guns, then proceed as follows....
* Put the flash in Manual mode, and the LCD readout should provide a whole scale showing which apertures are recommended for the respective distances from the flash to the subject.
* From the scale select a convenient flash to subject distance and position the flash accordingly. The aperture indicated is then transferred by you to the camera, which should also be in Manual exposure mode.
* Select a suitable shutter speed... (usually camera 'X' sync speed, whatever that is... typically 1/200th sec.)
* The scale on flash LCD should change automatically when you select select lower than full power output... that's if your flash allows reduced power settings... most do, but some don't.
* It should similarly change to accommodate different ISOs as they are selected.
As stated, this advice assumes your flash works in similar manner to the way most flashguns work these days.
Thanks, that makes sense. Though, I'm not sure that my 430EX works that way. In Manual mode, it doesn't seem to show the scale or allow me to select distance (or anything other than power). Could be that the 430EX, which is the consumer-grade model provides that much flexibility. Perhaps the 580EX does. If anyone knows, please let me know. (I'm also curious if, in that case, it works that way both on camera and as a slave.)