580 EX Built-in Wide Panel

The manual states that the wide panel increases flash coverage to 14MM. Suppose you aren't interested in a wide shot; will the wide panel act as a diffuser, throwing a less harsh light on the subject?

The manual also says that using the wide angle and the bounce at the same time throws off the display and results in an unnatural light as there is bounce and direct light at the same time. This makes no sense to me for two reasons. One, if the wide panel covers the head, there shouuld be no light thrown forward, as with a catchlight or index card. Two, isn't the bounce and catchlight effect a very desirable one?

Well, somewhat. However, I'd rather just use FEC for that. It's more handy just for wider shots, or for when you're using it close into an umbrella, for instance.

For one, the wide panel doesn't stop light. It "spreads it out", for lack of a better phrase. However, it also lowers your "effective" guide number. I'll just say that I've been displeased with the results when I accidentally didn't put the wide panel back in when I was using the bounce card. Just don't use the card on people with glasses. You won't like it.

>>wide panel act as a diffuser, throwing a less harsh light on the subject?<<

Diffusers act by increasing the apparent size of the source, not by increasing the angle of coverage from that source. Your source is identical in size, with or without the wide angle lens. The intensity of the light is reduced at the subject, merely because the total light is spread over a larger area, but harshness of the light is related only to the size of the source.

Regarding the use of the wide panel and bounce, what the manual was trying to say is that when you have the head pointed for bounce, say for example, 45 degrees, with the wide panel in use, direct light from the flash will partially light the subject (the top part but not the bottom part). As the head is pointed more towards the 90 degree position, you'll get less and less of this "edge spill" from the flash.