Well built and great image reproduction. I downloaded some software to check of all my images for the whole of 2015 & 2016, and rarely did I take pictures beyond 85mm, so I sold my 18-135mm to buy this and it has not disappointed. The loss in 85-135mm range is easily compensated by getting closer to the subject or if the need arises rent/buy the 50-135mm f2.8.

Well built and great image reproduction. I downloaded some software to check of all my images for the whole of 2015 & 2016, and rarely did I take pictures beyond 85mm, so I sold my 18-135mm to buy this and it has not disappointed. The loss in 85-135mm range is easily compensated by getting closer to the subject or if the need arises rent/buy the 50-135mm f2.8.

In process of returning lens as didn't deliver on expectations and issue with zoom:1. The zoom sticks from time to time at the start of extending and there's slight resistance at the end too - pretty sure it's the weather sealing that catches. Not sure if it upset performance but it was distracting and irritating. I've heard of others with zooms perfectly smooth throughout the range and yet others with zooms that stick slightly. Makes me question adequate quality control. I contacted Pentax and they gave varying responses to 'it shouldn't be like that' to 'try another lens of this type and see if it feels different'. Not the best help for a customer.2. Its a plastic body and didn't reek of quality. I've got some old manual lenses and it is remarkable how lovely they are to handle compared with such a new plastic lens. You've got to wonder if such a plastic lens will be going strong in 30 years time.3. Nice wide open and the lens has a reputation for being sharp. It is pretty sharp IMO, and maybe I've been spoilt with other lenses, but it was not as exceptional as I'd hoped for. As an example, I use a fujifilm x camera with its superior 18-55mm 'kit' lens which, while lacking the range of the Pentax, is faster and delivers better results. I was hoping for near prime performance and didn't feel it had this. Shame as the 16mm starting point gave a nice wide field of view.Perhaps my sample wasn't up to scratch. I wouldn't want to dissuade others from trying on the basis of my experience. I bought off Amazon marketplace so maybe the previous purchaser was disappointed too. It betters the Pentax kit zoom in range and sharpness, otherwise think I'll stick with my prime lenses, till something more tempting comes along.

In process of returning lens as didn't deliver on expectations and issue with zoom:
1. The zoom sticks from time to time at the start of extending and there's slight resistance at the end too - pretty sure it's the weather sealing that catches. Not sure if it upset performance but it was distracting and irritating. I've heard of others with zooms perfectly smooth throughout the range and yet others with zooms that stick slightly. Makes me question adequate quality control. I contacted Pentax and they gave varying responses to 'it shouldn't be like that' to 'try another lens of this type and see if it feels different'. Not the best help for a customer.
2. Its a plastic body and didn't reek of quality. I've got some old manual lenses and it is remarkable how lovely they are to handle compared with such a new plastic lens. You've got to wonder if such a plastic lens will be going strong in 30 years time.
3. Nice wide open and the lens has a reputation for being sharp. It is pretty sharp IMO, and maybe I've been spoilt with other lenses, but it was not as exceptional as I'd hoped for. As an example, I use a fujifilm x camera with its superior 18-55mm 'kit' lens which, while lacking the range of the Pentax, is faster and delivers better results. I was hoping for near prime performance and didn't feel it had this. Shame as the 16mm starting point gave a nice wide field of view.

Perhaps my sample wasn't up to scratch. I wouldn't want to dissuade others from trying on the basis of my experience. I bought off Amazon marketplace so maybe the previous purchaser was disappointed too. It betters the Pentax kit zoom in range and sharpness, otherwise think I'll stick with my prime lenses, till something more tempting comes along.

Had to return Faulty, But fab lens

Bought this as an upgrade to 18-135 WR and I've not been disappointed. Edge to edge sharpness is excellent and the loss of 85-135 is easily overcome by cropping, whereas the extra 2mm at the wide end is a real boon for landscapes.Some have commented that it is a bit larger and heavier than the 18-135 but I've not found it to be real issue (although I am used to hauling around a Sigma 50-500!!)

Bought this as an upgrade to 18-135 WR and I've not been disappointed. Edge to edge sharpness is excellent and the loss of 85-135 is easily overcome by cropping, whereas the extra 2mm at the wide end is a real boon for landscapes.
Some have commented that it is a bit larger and heavier than the 18-135 but I've not found it to be real issue (although I am used to hauling around a Sigma 50-500!!)

Outstanding quality lens.. I replaced a Pentax 17-70 with it and the sharpness has gone up very visibly. I did some tests with a test pattern and you can really see it. Very well made, silent focus.

Much superior to my Tamron lenses, which were good enough. Focusing quick and quiet and the Quick-Shift Focus is a boon. Weather-Resistant, too.