Advice on Flash and better beamer (1 Viewer)

Hello all,

This is such a wonderful forum about birding and bird photography. May its tribe grow. Reading thru tons of review here is what encouraged me to trade in my 100-400L and go in for the 400mm f/5.6 lens. I'm not disappointed. Its a fantastic lens.
Now for my questions:
a) I feel that a flash ideal for bird low light situations with this lens. Do correct me if I'm wrong. What would be the reach with a flash only.

b) What flash would you recommended for this lens. The bodies I use are:
a) 1d Mark2
b) 550d
I'm on a budget and would like to go in for a 3rd party brand. The canon one is expensive.

c) Does a better beamer also help with this lens?

All advice is useful

Range of the flash with and with-out Better Beamer depends on its output power (aka guide number). The BB will boost the range by focussing the light into a smaller spot. How far a flash reaches depends also on parameters such as ISO, shutterspeed, aperture ...... No specific answer possible, just that one can assume using a BB will give ~2 f-stops more range (double the distance). Check this link for some info: http://www.naturescapes.net/docs/index.php/articles/81

The only requirement for the lens to work perfect with the BB is to be longer than, I think, 300mm. With shorter lenses the frame will show vignetting as the light spot generated by using the BB is smaller than the area covered by the lens. Still not a deal breaker if one can accept the dark corners.

Flashwise I would recommend looking for a TTL controlled flash with high speed sync. (for using higher shutter speeds than the camera's generic 1/250s), and a guide number as high as possible to max range.

I use a Sigma DG610 Super that offers above mentioned features for ~$250.
Some of the even cheaper flash guns from China (e.g. Yongnuo etc.) offer TTL control but as far as I know lack high speed sync (as does the cheaper Sigma DG610 ST). Metz is another company that offers various flash models and likelt one will meet all the requirements.

Ulli