[bccl626]

請問聲:輔廠鏡來說, 那個牌子有信心些?
Sigma, Tamron and Tokina.

[Obi-Wan]

It's very difficult to compare lenses from different brands unless for the same price range, focal length & f stop, e.g. Canon, Nikon also produces significantly low grade lenses as well as highest grade lenses. Same for sigma & tamron.

I have used the 28-70/75 f2.8 of Tamron, Sigma and Tokina, all of them produces very sharp images after step down to f4 or f5.6, if open wide at f2.8 the quality is
Tamron > Sigma > Tokina

therefore for the same price range / focal length / f-stop, I guess Tamron > Sigma > Tokina

But one thing u should be reminded, these lenses sometimes have trouble in focusing at low light. That is the focusing accuracy is somewhat lower that the original brand