Pros:optical quality, pocket-sized, fast focusing, f1, 4
Cons:contrast at maximum aperture
Opinion:The lens can be used since the maximum aperture, you lose a little contrast to the spherical aberration which veils the image slightly, from f2 significantly better at f2, 8 had already reached the maximum performance to remain constant up to f8. Note the defects front back focus on some of the bodies that do not have adjustment can be a big problem. The construction is good, but suffers from a design rather old. The bokeh on my specimen is beautiful, smooth and jitters, but trying other examples I've found variations. The focus is very fast but not always very accurate I think this should be attributed to the Pentax AF system. In everyday use a lens to have because it is very small and portable, use in low light adding that it is stabilizzta directly from the camera is godibilissima even if the crop dell'apsc it distorts a little when the function is originaria.rnAl discontinued (no more imported in Europe for environmental problems) but are still carriedmplari new although higher prices.
Pros:image quality, construction, sealed, constant aperture of f/2.8
Cons:AF motor defective in several specimens, slow AF, only suitable format APSC
Opinion:In this pro zoom I put the image quality and this is his main gift, with this view seems to use the fixed from 50 to 135. At the time, I never had this quality in a telephoto zoom lens that starts at 2.8 and note the maximum aperture you have great results at all focal lengths and across the frame, even if slightly decreases the focal length of 135. The build quality is very very good even though I've seen better, the focus is slow but always very precise (tried on various bodies) the big trouble with this view is the AF motor prone to breakdowns also repeated (it is one of the first ultrasonic lenses produced by Pentax) and in the first matches of objectives, the failure rate was quite high although it seems that lately we have put a piece. For the cost quite high and the lens to which it addresses the objective this defect is, however, absurd and bearable only for the high quality that offre.rnHo found here as well as on the 16-45 resistance to flare suboptimal speciesand with the light source off camera (always mounted hood) in some cases the image is unusable. I do not really suited to the optical format only APSC but this is the only one that can make a difference in some situations and sopportandone defects can only give satisfaction.
Cons:short focal length, diffilcoltà of some specimens to focus at minimum range, embarrassing games on the barrel, only suitable format APSC
Opinion:Although not having this point I could use it for a couple of years, the building leaves much to be desired and lacks the sealing was found in most specimens a certain difficulty in focusing at minimum focus. That said optical quality and at a good level, and taking into account the price at which it is used may be a good upgrade to the 18-55 standard. The colors and sharpness are excellent especially since the maximum aperture at 16mm focal length decreases slightly to maximum 45mm. Diaframmando there is an increase in performance and decrease in vignetting at f8 images are sharp at all focal lengths and on almost the entire frame. The colors are warm in style Pentax, on my copy I noticed an imperfect seal species to flare with the source of light almost out of frame.