If you've ever had the problem of not being able to get everything into the frame, an ultra-wide angle lens may be the solution. The Pentax 10-17mm ƒ/3.5-4.5 IF SMC P-DA Fisheye is one such lens, offering up to 180 degrees of coverage when set to 10mm. The lens has an effective focal length of 15-27mm when mounted on a Pentax digital body. As a designed-for -digital lens, it will mount on older Pentax film bodies, but there's no aperture ring so it won't work properly if the camera can't set the aperture. Further, the glass elements are designed for the smaller APS-C sensor, so vignetting will occur at the wider focal lengths. But if you're fine with these caveats be prepared for some really wild barrel distortion, as the lens produces results which don't attempt to correct for distortion - the ''fish-eye'' effect. Read the whole review here.