So Im looking over the Speedlite 430 Manual and another source and discover that P, Av, Tv, Night and Auto modes do different things.
In P mode, if the ambient is fairly bright (above 13 EV), it assumes you want to fill flash the foreground and the flash fills in the foreground; if the ambient is not bright (below 10EV), it assumes you want to illuminate a subject in the foreground and in both cases you end up with an undexposed, dark background. ...Out with P, Auto and A-DEP modes then unless you dont mind a horrid background, as a rule, unless the background dosent matter because its a white or plain background like in a studio setting.
In Tv mode, unlike P mode, the flash tries to illuminate the background adequately, but will often underexpose the background on A body cameras with the E-TTL flash unit engaged. The solution offered is to compare the Apeture settings in M mode, revert back to Tv mode and apply the apeture setting M offered and use Flash Compensation.
Im thinking that you wouldnt want to worry about using Tv mode unless you wanted to deliberately slow down the to get a milky water effect on sea or waterfalls shots and the SS impact of Speedlites makes is sooo much faster than normal SS without a flash so out with Tv Mode unless you want to slowww down movement (ocean, waterfall, nightflares on cars).
In Av mode, you get much better control of the depth of feild, so macro shots and landscape shots and shooting in places with awful backgrounds you want to blur would be suited to the Av mode. The Flash takes care of the SS concerns (especially if mounted on a ) in dark conditions, but again the flash acts a a fill flash in order to expose the background correctly. Im thinking this is a good mode to use because the Apeture and consequently and limitations of the focal length sweetspot range are controlled for.
SO I AM WONDERING IF MOST PEOPLE USING FLASH OPT FOR MANUAL MODE as a RULE ?
Why would I say that ?
Im thinking that in manual mode you get alot more control over the shot. You use the cameras Apeture/ combination manually adjusted to account correctly for the overall AMBIENT conditions of the BACKGROUND as you would do without a Speedlite attached, and you can use the Speedlite flash to illuminate the SUBJECT.
You direct the flash to off the main SUBJECT (eg a person) by using the Flash Lock to find the subject and lock it in so it calculates the correct flash output level for the shot.. If you dont like the outcome you use the Flash Compensation to adjust the flash output level up or down a third or half , and bang, shoot the image again.
Seems to me that M mode gives you all the benefits of Tv (movement control) and Av (Depth of Feild) for flash photography, avoids the background horrors of P mode and offers much more flexibility and range in controlling the for the image.
Hope someone can confirm the above understanding of the impact of camera Mode selection in Flash Photography is right and confirm that M mode, as a rule, is best for flash photography.