Hi Valk85
Assuming your a65 came with the 18-55 kit lens, you should probably be looking at a 55-200 telephoto zoom. Sony's SAL55200-2 is a compact, lightweight companion to the 18-55. Tamron and Sigma also make alpha-fit 55-200 zooms that are significantly cheaper than the Sony, although the Tamron is a rather old design now, and the Sigma won't match the image quality of the other two.
If you don't have a kit lens, or are looking to replace one with a full-range zoom, something like the SAL18200 is roughly equivalent quality to the 18-55 kit lens and being a 18-200 would serve as a single all-in-one wide-angle to telephoto zoom. Again, 3rd-party 18-200 lenses may be worth looking at.
If you have your eye on a particular one and need further advice, fire off a reply here and I'd be happy to help.
Cheers
Mick
