Are there any new lens` you can buy for this camcorder with better zoom facility ?

there are add on lenses such as telephoto or wide angle lenses which attach to the stock lens but you cannot replace the stock lens on the a1 or the g1.

Are there any new lens` you can buy for this camcorder with better zoom facility ?

Rob has given you the answer already, but a 20x ratio zoom lens with the quality of the XH-A1's is actually pretty good going as it is. Once you get much above that range, there are some pretty serious compromises in an affordable lens. Anyway, when using a significantly longer focal length, you start getting into problems with tripods (they have to be VERY good) and nae chance of a handheld shot.

If you search dvinfo you will doubtless find threads on telephoto adaptors for the XH-A1. I've only got the Canon wide angle (and the muscles to prove it).