I have had several tripods over the years all of which had Pan and Tilt heads. I am currently looking to buy a new light-weight tripod. I currently favour the Velbon Ultra Luxi SF for its' sheer compactness. I have never had a tripod with a ball and socket head. Can anyone enlighten me as to the advantages of ball and socket tripod heads? Bearing in mind I use 35mm SLRs with (occasionally) heavy 'long' lenses is this the way to go? Or should I stick with pan and tilt?