Pentax smc P-DA 12-24mm f/4.0 ED AL IF Lens

This lens gives an exceptional performance on any Pentax KAF2 mount DSLR. It is not suitable for 35mm users as the image circle is only designed to cover the area of an APS C size sensor. 35mm users may get away with using it at longer focal lengths without vigneting. The lens's focal length equivalent in 35mm is 18 - 36mm. The lens maintains a constant aperture (F4) throughout zooming; many of it’s rivals do not offer this. Many independent reviews rate the performance of this lens as highly as, or more highly than it's Nikon and Canon equivalents. It's build quality is good, but not as good as Pentax used to offer, nor as good as the Nikon digital zooms I am familiar with. The movement of the zoom and focus rings could be smoother. It is quite a large lens for a wide angle zoom, but so are the competition. (77mm front filter size). I have read in many places that the Tokina lens of the same specification is this lens re-badged Pentax. I have never compared the two physically, but the optical specifications are identical. I think this lens offers excellent value for money, the Tokina branded one usually sells for a lot less, an will be available in Nikon, Canon and probably Sony Alpha and other mounts.