Comparing the Sigma f2.8 mid zooms
More recently, after my first ever positive experience with a Sigma lens in its price class, I decided to explore more Sigma lenses in the hope of finding those that could truly be worth buying.
In general, I still recommend people buy Sigmas only after thorough investigation, else stick to Nikon.
These 2 Sigmas have impressed me, each in their respective price class, BUT (a big but here)
only for use on DX crop frame cameras.
The 18-50mm f2.8 is a DC which is designed only for DX anyway, but the 24-70 is an FX compatible lens, yet I have not tried it on full frame, & frankly, I doubt it will be as good as Nikon
Main characteristics
Sigma 18-50mm f/2.8 EX DC
Designed to work with all DX frame cameras.Has a built in AF motor so will autofocus with all DX cameras.
Will show significatn vignetting (dark corners) if tried on DX at any focal length
Light transmission is not as good as more expensive f2.8 lenses
So at f2.8, this is more of an f3.2 when compared to my Nikon 18-200mm lense as well as the Nikon 35mm f1.8 G
Sigma 24-70mm f/2.8 D
Will work on DX & Full frame FX.The older version without the AF motor will not Autofocus on DX cameras that dont have their own built in AF motor
