MJL Photo wrote:
Anyone have any info and/or suggestions for an external pattery pack for
Canon 550 flash?
Quantum, Norman, etc...

We have a Turbo C and a Turbo Z from Quantum and use them often for
fill-flash with the 550EX for birds etc ... highly recommended (the
Turbo Z is no longer made).

How about power and costs.

More power, up to 8x faster than with normal batteries ... not cheap,
that's for sure.

Good / bad experiences.

Other than the extra weight and unwieldness and cost there are few bad
things to say You might glean some good info from this comparison
article ... http://www.rpphoto.com/howto/view.asp?articleID=1018 ...
one problem my wife faces with the Turbo C is if you clamp it to the
bottom of the camera it throws off the balance a bit so we work out
ways to connect it to the tripod or head. The others mentioned in this
article are pretty heavy, 2 lbs or more ...

Is it really workth it?

Do you need to shoot a lot of frames consecutively with flash? If so
they are worth it ... if not then they are not worth it ... we have 8
frames/sec cameras and use the 550's for close range fill flash so the
batteries are essential for us, but for many types of photography they
aren't needed.

Bill