Pentax-A 28-135mm f4 used to be an expensive precision instrument originally designed for film cameras. Now we can get one for about US$60 owing to popularity of digital photography; many old lenses become obsolete. In manual mode it still works fine with many digital cameras. With Pentax K-3, the lens and camera become a well balanced system. It is heavy since it contains lots of glass. It has a nice constant aperture of f4, and a useful range (for general landscape photos and portraits) plus macro.