Review on Pentax 16-45mm f/4.0 SMC PDA ED AL Zoom Lens: Compatible with Pentax and Samsung Digital SLR Cameras by Bethany Baker

I think this lens will become a Pentax classic. There's nothing very sexy about that. It uses an old Pentax screwdriver-in-slot autofocus (unlike their new HSM in-lens), its maximum aperture is just f/4, and its zoom range ends at an odd point, 45mm (equivalent to 67.5mm on a Pentax -DSLR). - Slightly less than the traditional portrait length. It lacks the build quality of top-of-the-line Pentax DA* lenses. It is not weatherproof. But at this price it's a gem. The build is decent, and by using plastic instead of metal, the autofocus motor in the camera rather than the lens, limiting the aperture to f/4 and the zoom range to 3X, Pentax has kept the lens light and small. It's not expensive, it has a constant aperture, the autofocus is fast and accurate, and (most importantly) it's optically superb. I already have a Pentax DA* 50-135/2.8, great zoom and was thinking of buying a DA* to match. 16-50/2.8 but I was put off by reports of poor quality control at 16-50. So I bought 16-45 instead (and half price). When it arrived I tested it by shooting a tabletop still life including a test piece with my Pentax 21mm, 31mm and 40mm Limited Primes at all apertures from f/4 to f/16 and then taking the same photo with a zoom to the same focal length and aperture. In almost all cases 16-45 corresponded to fixes in the center and sharpness even at f/4. Yes, primes are better - they have better angles, less vignetting, more overall contrast, an undefinable "click" that produces primes, which I call the Pentax Look. And yes, the zoom has an optical flaw: Blue-yellow color fringes in places where light and dark areas overlap. (Rarely a problem, but it's there.) I stick to my prime numbers. But when the subject is dynamic rather than static - like a party or social event as opposed to studio or landscape work - Zoom is just the ticket. I am confident that this lens will produce good results that are indistinguishable on most prints from what I would get with a prime lens. If you can get by with f/4 and don't mind paying less for more, I recommend this lens.