| Latest Review Posted | Sigma EX DC HSM 17-50mm F2.8
I owned pentax 16-50 f2.8 for 1 year, and then I sold that bought this sigma 17-50 f2.8. so I have pretty good understanding of both lens.
I am looking for better sharpness f2.8 standard zoom instead of weather seal, build quality kind thing.
That is the reason bought this.
build quality: sigma is very high, but have to say pentax is even better and look better. pentax is also weather seal. big plus for pentax. however because of the 2 inner tube design, the zoom ring operation isn't super smooth. sigma has better smooth zoom operation. both lens has pretty smooth focus ring.
auto focus: sigma might have slightly faster speed. but to be honest 16-50 has pretty fast SDM speed. I feel it is hard to notice the difference in the field. focus accuracy based on my experience, pentax has better keep rate. sigma seems has difficulty focus on far away infinity subject. sometimes it miss. pentax has no problem at all.
also sigma has only 30 degree turn of focus ring. pentax has about 45-60 degree. so if you use manual focus, sigma is not as good as pentax.
also sigma does not have quick shift. and the focus ring rotate when auto focus. so pentax is better here.
sharpness: ok, this is the main reason sold pentax to got sigma. and yes, sigma is better.
after f4 or even f3.5, there might have little difference. but at f2.8, sigma is better.
overall I find the resolution chart at photozone is pretty accurate.
sigma has reverse zoom ring and focus ring. definately need to get used... |
