If you have a Pentax camera with a smaller-size APS-C sensor and K mount, then the Sigma 18-250mm f/3.5-6.3 DC OS HSM is an incredibly versatile lens that is a real jack-of-all-trades lens you can carry in any situation. With a focal length spanning from a wide-angle 18mm up to a 250mm zoom, with macro capabilities to boot, Sigma's 18-250mm could easily be your camera's first all-in-one lens, or a great replacement for several smaller lenses that you're looking to consolidate.
