Wow, well done

Agreed, a record shot has to be a true record, but with anything else I class it as art and it's all up to the photographers intention.

Here's a link (NSFW) to a before and after of one of my recent shots , the after is what I saw in my mind and how I felt when I took the image, sadly the camera recorded the before imge on the left and I had to help the image along to get it to what I remembered seeing.

Beautiful images, I was in Trondheim recently and the light was lovely, I was even still shooting at 11:30pm!

Focusing, it's something I fought with for ages. I used to get quite a few images that were back or front-focused, so I would calibrate all my lenses, but still get issues, and re-calibrate them again, and again. It's not just a Pentax problem, or to specific lenses, I've upgraded body and lenses and the problem is still there. I know photographers with cameras from all major brands, and I see their prints close-up at the camera club, and I see lots of back or front focussing. Images are satisfactorily sharp, but they could be sharper, and the focus is not precisely where the photographer wanted it!

Calibration helped, but I'd still get some duff ones, without rhyme or reason. So now when I am shooting wide open with any lens, which is probably 90% of my images, I use live-view focusing, problem solved in an instant.

So to answer your question Alan I did not find that it suffered more than any other lens, it's probably more noticeable as it's 1.8 throughout the range.
To answer Defragged, I think the Sigma 18-35 and Pentax 50-135 are the two sharpest lenses I own (followed very closely by the Tamron 17-50 I've just sold!), I use Photozone.de whenever I am thinking of buying any lens. The 18-35 and 17-70 cover different ranges, so you need to go with what you are likely to shoot.

Now as I'm rambling on and we're off topic, I may as well continue. I do lots of talks to camera clubs, and my talk is all prints. I often get asked at the end whether I shoot Canon or Nikon, when I say Pentax I have had a response "Pentax, is that a Canon or a Nikon"!
I also often get complimented on the sharpness and quality of my prints and am asked how I do it as they can't get the same quality - even with full frame! First it's about being obsessive getting the focus right, and ditching images where it's not, and also shooting wide open tends to separate the model nicely from the background, giving her an increased perceived sharpness. On more than one occasion I've had people ask whether I used medium format to get that sort of quality. No bad from a little crop sensor Pentax

Thanks for buying all the lenses, and what was the question???

Hi Defragged

I think it's an excellent lens in every respect, albeit a little larger and heavier than the 17-50 it replaced.

This Gallery Image- NSFW was taken at 1/30s F1.8 handheld, and I got it printed at A1 and it hangs on my landing, and it's pin sharp edge to edge. Can't ask more than that

All now SOLD, thank you, enjoy the lenses gentlemen

Thank you Andrew.

Just the Sigma 30mm 1.4 left, no sensible offer refused, cracking lens for shooting in the dark

55-300 SOLD

Any reasonable offers accepted

Tamron 17-50 SOLD