i am looking at purchasing a 17/24-70 2.8 fast zoom for my K5. my dilema is , that the more i read and research these lenses, the more i cant decide. all have pros and cons. i am after a good quality, fast, sharp lense, for mainly outdoors, landscape, low light, candid, opportunistic type photograpy. a good quality, reliable, best bang for your buck everyday walkaround lense. it has to be a zoom, not a prime(i have a 50 1.4 which is nice) and it will be complimentry to the 70-200 2.8. i currently use the da 18-135 as my walk about lense, also have a da 10-17. i would like to hear from anyone who has used any of these lenses, especially on the k5, as to what they really perform like. any recomendations much appreciated.
the lense options are as follows.
pentax smc da 17-70 4.0 ed sdm
sigma 24-70 2.8 if ex dg hsm
sigma 24-70 2.8 ex dg macro
sigma 17-70 2.8-4.0 dc macro os hsm
merry xmas & happy new year