Sigma 17-70mm f/2.8-4 DC Macro OS HSM
I have an older version and have found it very good, a notable improvement over the kit lens.
I have the older version too and love it to bits. Superb value for money. very very crisp, very close focus and one of my most used all rounders.
And yes it's leaps and bounds ahead of the Pentax kit lens.
If you get one, don't forget to check the AF calibration for it in the cam though.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
It's soft at 17mm until f8 but from 20-70mm my older version is quite sharp even wide open and prime quality at around f4 - f5.6. Never seen any purple fringing. The only thing that could be better at the price is AF decisiveness in low light (on a K-30) although it still beats the kit lens, but I imagine the newer HSM one fixes that.
Mine isn't.

[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
stevewebb
Member
North Wales
I have a Pentax K30 and I'm looking at getting a lens upgrade. I have seen a Sigma 17-70mm f/2.8-4 DC Macro OS HSM Lens
Would this be a good buy or can anyone recommend something else?
I mainly take landscapes and now got into star and night photography using bulb settings etc.
Many thanks
Steve
Pentax K30 - Sigma 28mm f2.8 - Pentax 50mm f2.0 - Pentax 17-55mm WR - Sigma 17-70mm DC OS f2.8