Canon 380EX zoom behavior on 350D

I just noticed some quirky behavior in the interaction between my Rebel XT and

my 380EX flash. When the lens (17-40 4L) starts out at the wide end, and zooms

out to the normal end, the zoom on the flash changes to follow the lens

setting. BUT, it does not behave similarly in the opposite direction. If the

lens starts at the normal end (40mm, 35mm on flash), and zooms wide, the flash

stays at the original zoom setting until you change camera modes or cycle the

power on the camera, and then it adjusts to the lens zoom setting. I assume

this is normal behavior, but odd, huh?

 

Examples (---> indicates zoom direction)

 

Lens: 17 ----------> 40

 

Flash: 24 ---> 28---> 35

 

 

Lens: 17 <---------- 40

 

Flash: x -------------35

Just tried the 5D/24-105/580EX. It behaves in a similar way, initially the flash follows the lens but only in one direction. When changing direction of the zoom the flash stays still. Pressing the shutter button halfway activates the flash's zoom head. I have no idea why this was implemented in this way.

I suppose it is because it doesn't matter as much if the zoom head is zoomed wide for a narrow shot, but it would make a big difference if it was zoomed narrow for a wide shot. You just get less illumination over a wider area for the former scenario, whereas the latter scenario could result in splotchy uneven lighting.