| Latest Review Posted | Sigma APO DG 170-500mm F5-6.3
I'm writing this to restore a real status quo. Sigma 170-500mm F5-6.3 APO DG is not 10-rated lens. Not at all.
I have to admit that for some time I've been obsessed with two discontinued Sigma lenses: 400/5.6 TeleMacro and 170-500mm 1:5-6.3 APO DG RF. Although 400/5.6 TeleMacro is real deal, the latter is a mystery. According to the Sigma's list of recently discontinued lenses there are only two variations of 170-500mm 1:5-6.3 lens: APO Aspherical and DG APO Aspherical. Both lens designs looks identical. The newer DG version has additional digital coating. That's all. The lens what has been rated 10 here used to be additionally marked as RF special version. I strongly believe that the RF marked variant does not exist at all. Since than I contacted PF administrator, and Adam removed controversial RF letters from lens description.
However, why both DG and non-DG versions are rated so differently here?
Trying to solve the mystery and not expecting too much I purchased Sigma 170-500mm 1:5-6.3 DG APO Aspherical mostly out of my curiosity, having an option to return it back to KEH.
The first surprise: at 170mm my K-5 reads aperture as 4.5 instead of 5 by the spec and - 6.7 instead of 6.3 at 500mm.
Second surprise: the output at 500mm is very sharp.
There is a quick target set-up for shoot out and the best 100% crop. Please note that the best results was achieved not with regular PDAF, but via MF Live View focusing.
https://www.pentaxforums.com/forums/members/43571-... |
