Sigma continues to make the most appealing options available when it comes to ultra wide angle APS-C camera lenses. The 10-20 f/4.0-5.6 EX unites an attractive price combined with excellent optical performance. That's the reason many people were surprised by Sigma's announcement of another wide zoom, with the identical zoom range, although somewhat faster than the previous model, bring f/3.5 through the entire zoom range. A bigger aperture means of course that the lens has become physically bigger, heavier, and more costly than its slower brother.
The lens' build quality is superb. It includes the crinkle style surface, a characteristic of EX Sigma lenses, both the zoom and the focus rings are damped, with the focus ring being somewhat stiff. We can give credit to the sonic wave powered AF (HSM) for allowing the lens to autofocus on all present day Nikon DX DSLR cameras (including the
motor less starter cameras). Representative of HSM drives, focus can be overridden manually at any time, although the lens is a G-type that doesn't provide an aperture ring.
While zooming, the lens extends somewhat and It's at the shortest length at approximately 15mm, a little bit extended at 20mm while at it's greatest extent at 10mm. The inner moving tube is especially solid, as there's no wiggling compared to Tamron lenses. There's no front rotating while focusing so polarizers work great. However, the biggest bugaboo is that it takes expensive and huge 82mm filters.
If you're accustomed to the way Nikon lenses, function the focus and zoom ring on the Sigma feel "just wrong" as they rotate in the opposite direction, while Canon users will feel right at home. One other minor improvement over its older brother is the added AF/M switch.
This newer Sigma 10-20mm f/3.5 EX HSM DC lens leaves us with diverse feelings. The lens' build quality is most excellent, the distortion is a bit excessive at the wide range (but excellent during all other areas of the zoom spread), there's also quite a lot of CA and vignetting, although that's usual for this class of lens. Center resolution is near perfect, there's no complaint's about the borders and corner operation is just okay at 15 and 20mm, but really disappointing at 10mm. This lens makes one wonder just who's the customers for this lens. Those already having the slower and older 10-20 will most likely won't feel any necessity to upgrade, particularly if they already have filters that fit the lens. Still those who are in the market to buy new will no doubt find the older model with its lesser price
threshold more appealing. Unless you actually have a need the extra speed, although in those situations the Tokina 11-16/2.8mm might be the more attractive choice.
Still, those who go ahead and acquire this lens will have purchased a solid performing lens, which provides great results if you have knowledge of its short comings and function around them.