Best Flash for Wildlife/Birds?

Hi,
I posted this on the Wildlife forum a few days ago without getting any replies, so I thought I'd try this one.
I have not used flash in my wildlife/bird photography but am planning to start doing so. I shoot mostly with a 7D and 100-400. I have an old Canon 420EX. As with wildlife lenses, I assume the more power/range a flash has, the better. What would be the best flash for wildlife? Some of the specs of the Canon 600EX-RT seem to suggest it would be the best choice, but it is expensive and I don't know how much difference it would make in the real world. I'm assuming I'd want a Better Beamer as well.
Thanks for all advice!

Dear Steve,

If you think you need a Canon flash then get the biggest and best that you can afford.

I have two aftermarket flashes, a Sigma EF-530DG and a Promaster 7500DX. They both provide well exposed pictures on my 20D, 40D, and 1DMK2. I haven't sprung for a Better Beamer because most of my work is in the backyard and I can get closer. Personally, I think a bit of ingenuity and a little bit of effort will allow you to fit a Better Beamer to many more flashes than it is designed to fit, but I'm a cheap SOB.

I'll let you know how things work out for me when I get one.

Regards,

Tim Murphy

I've used 420EX, 550EX 580EX and 580EX II

In all honesty, all of the 5XX models were pretty much the same as far as being up to the task.

The 580ex has better recycle times and better high speed synch (required for a lot of wildlife work) over the old 550.

The 580 EX II added weather sealing, direct camera control, and some other doo daads,

..but I use both 580 models interchangeably now and can't see any huge reason to prefer one over the other.

If $$ is a concern, but you want to get Canon, the 580ex used can be had for well under $200.00 (compared to about $600.00 for the 600EX!!!)

What you really need to do when you get your flash is to get a "Better Beamer" to go with it, and an off camera cord and bracket to prevent "steel eye" (red eye for birds, but it's not red)

Thanks for the comments. I'll probably stick with Canon, as I have a phobia about 3rd party gear perhaps not being able to take advantage of all the Canon functions. Looks like it's coming down to the 580 II or the 600 for me. Just have to decide if the 600 is worth the extra $$. Seems like that is always the question.