I would like to try using a tripod for bird photos and was wondering which head unit is the best to use? Is there one head type that is good for most styles of photography or do people have a few different types of head for different pics. I have an EOS 50D with a 100-400L series lens which is reasonably heavy so I will have to get a head that can handle that weight. I already have a Benro A358 M8 tripod that I have not yet used.