I bought this lens for a trip to Africa to photograph animals. The focal length range is very good, KB = 600 mm is already a word. The lens is measured by really small, especially considering that a 500-mm full-frame lens is half arm length and weighs several kilograms; over the cost we would not think about. The lens is able to provide sufficiently sharp images, but you must be clear about that, the yield of really sharp images is not very good, at least with the current standard Panasonic cameras (in my case a GX1 and a G3). The autofocus is strongly demanded, and a manual focusing is not easy (you can of improvement with new cameras that have better viewfinder, hope, for example, Oly OM5). This becomes a problem if, for example trying to put on an animal sharp and few blades of grass in the foreground. Because of autofocus gets out, and until that has refocused manually, the cattle elsewhere. Likewise, one must accept that the lens is not suitable to be used in a dusty environment. When zooming the thing is pumping properly air, you can feel the draft clearly, when you have the camera on the eye. The zoom ring has a non-uniform resistance, depending on how you hold the lens. This can be very annoying. When the lens is facing downwards, the zoom setting adjusts by itself; not particularly pleasing. Nevertheless, the objective is worth a recommendation. In low light conditions, you can make extraordinary images (especially if there are no obstacles between photographer and subject), without having a "hard-core" equipment hauling with them. For casual photographers who want to capture your pets on vacation, the lens is ideal, above all in view of the moderate price. Professionals and extreme enthusiasts are not happy with this lens, however.
