[quote name='Xastoul' timestamp='1322053061' post='13195']
Good, I tought I better of start with fixed focal length to have a better quality and a lower price. I just don't want to invest a lot on a lens and end up with something I don't need or don't fit to what I'm doing.
Thanks
[/quote]
For portraits, I'd get the 50 f/1.8 G.
It's very affordable and offers great bokeh control at f/1.8. It's also quite good wide open already.
Otherwise, I own the Sigma 17-70 f/2.8-4.5 (old version, supposedly sharper than the OS version) and I find it to be an excellent lens. Stop it at f/4 and it's excellent and even f/4.5 at 70mm is sharp enough for portrait. At f/5.6 it's tack sharp through the whole focal length. Plus, you get pseudo macro which is extremely convenient. It can still focus when the subject is 1cm from the front lens element! To me, it's the most versatile lens I own as it combines a great range, good sharpness, pseudo macro, it's 2.8 from 17 to 21mm and it features good bokeh, flare resistance and CA control. If only it was weather resistant <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='
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These were all shot with it:
[url="http://capturedbyflo.com/details/h5ff42e7#h5ff42e7"]Macro[/url] @ 70mm f/7.1
[url="http://capturedbyflo.com/details/h12caafe5#h12caafe5"]Macro[/url] @ 70mm f/6.3
[url="http://capturedbyflo.com/waterscapes/h2930d14a#h2930d14a"]Landscape[/url] @ 17mm f/5.6
[url="http://capturedbyflo.com/flora/hbd85785#hbd85785"]Macro[/url] @ 17mm f/2.8 (nice DOF)
[url="http://capturedbyflo.com/landscapes/h1f478b97#h1f478b97"]Landscape[/url] @ 17mm f/10
[url="http://capturedbyflo.com/waterscapes/h3afafb0e#h3afafb0e"]Landscape[/url] @ 37mm f/10 (flare resistance)
[url="http://capturedbyflo.com/candids/h2f4ba36a#h2f4ba36a"]Landscape[/url] @ 26mm f/5.6 (flare resistance)
[url="http://capturedbyflo.com/nature/h259523b2#h259523b2"]Landscape[/url] @ 48mm f/8
[url="http://capturedbyflo.com/nature/h451bb40#h451bb40"]Wide angle[/url] @ 17mm f/6.3
And a couple more landscapes at 17mm f/8: