Summary: Nice lens. Smooth zoom. Construction looks and feels solid. Good image quality for a long zoom. This lens is VERY loud. I almost returned it due to the noise alone but I decided not to when considering cost, quality and other lens in this price range. I use it on a pentax k3 and the auto focus seems to hunt a little more than I would expect but not bad. In general I like it and it is a good buy.
Glenn A. Martinez "Glenn Martinez Olomana Gar..., Amazon
18 August 2014
Summary: It is well made and VERY sharp. Wish it had a fast lens and wish it did 18 to 300. That would make it the perfect all round lens. I sent it back because it can only focus about 5 to 6 feet away from the object. Bought a lens that focused within 13 inches, but alas, it is not a Pentax and not weatherproof. And almost as sharp.
Summary: I bought the lens because it was weather resistant but the lens was just not up to par when it came to sharpness it's just an average lens especially at 300 millimetres which was the most important for me
Summary: I was quite happy with my Pentax 55-300 lens until I had it in a padded camera backpack, the backpack slipped off my shoulders and landed on the ground and when I opened it, my lens was barely hanging onto the body of my KX. Lo and behold, I found the lens mount ring was made of PLASTIC, not metal, and it had broken. I checked my other Pentax digital lenses and my old film lenses too, and none of them had the cheap plastic lens mount ring.
Excerpt: I've had this lens for over a year and have always had relatively disappointing results. IQ has been mediocre at pretty well all settings. Looking at reviews of the lens on this forum and elsewhere, I doubted my results, attributing the poor IQ to camera shake, field conditions and so on. So I placed my K-7 with the 55 - 300 on a tripod and tried again. The results were not very different.
Pros: Light, compact, has quick shift, storable lens shade