The Sigma 30mm F2.8 DN ($199 direct) is one of a trio of lenses that Sigma produces for mirrorless cameras. This model can be purchased for Sony NEX or Micro Four Thirds cameras, and delivers a slightly different shooting experience depending on the camera with which it is used due to the differing sensor sizes in the systems. We reviewed it on a NEX camera, where it delivers a 45mm (full-frame equivalent) field of view, but if you shoot with a Micro Four Thirds camera the smaller sensor makes it more like a 60mm lens.

The lens itself is impressively compact. It measures just 1.6 by 2.4 inches (HD), weighs in at 4.9 ounces, it supports 46mm threaded filters, and a reversible lens hood and soft case are included. It can be had in silver or black, and the metal barrel gives it a solid feel. The large focus ring is smooth, which isn't my preference for manual focus control; a ring with ridges or a similar texture provides a better grip. The minimum focus distance is 11.8 inches, which makes it a far cry from a macro lens. NEX shooters would be better served with the Sony 30mm f/3.5 Macro($273.00 at Amazon) if close focus is a concern; its aperture is only a half-stop narrower and it can focus to 3.7 inches for 1:1 magnification. As is the case with the Sony macro, there's no optical image stabilization, you'll need to move up to the Sony 35mm f/1.8($473.00 at Amazon) to get that in the NEX system. Micro Four Thirds shooters with Panasonic cameras may also want to consider a stabilized lens, but Olympus cameras feature in-body stabilization.

I used Imatest to check the sharpness of the Sigma lens when matched with the APS-C Sony Alpha 3000($439.99 at Amazon). It's one area where there are no disappointments. At f/2.8 the lens manages 2,144 lines per picture height with sharp edges and minimal (1 percent) distortion. That's better than the 1,800 lines we require for a photo to be called sharp. Performance increases gradually as you narrow the aperture; it peaks at 2,256 lines at f/5.6. At corresponding apertures it outperforms the Zeiss Touit 1.8/32 for NEX. The Zeiss is more expensive, but it captures more than twice the light as the Sigma at its widest aperture.

You can't argue with the value for your money that the Sigma 30mm F2.8 DN delivers. For less than $200 you get a compact, standard-angle prime lens that is sharp from edge to edge at every aperture. But there are a couple things that you miss—image stabilization and close focus to be precise. If you're a macro fan, the extra $80 you'll spend on the Sony 35mm Macro is worth it, and its f/3.5 maximum aperture is only a half-stop narrower than the Sigma's f/2.8. But if you have the money, the Sony 35mm f/1.8 is your best bet for a similar lens in that system—it has the same close focus limitation as the Sigma lens, and it's not super sharp at f/1.8. But it does deliver solid performance from f/2.8 onward, and stabilization will let you shoot at narrower apertures and still get a blur-free image.

Micro Four Thirds photographers have fewer options in the 30mm focal range. Olympus's lineup has a 17mm($349.00 at Amazon) lens and a 45mm($499.99 at Amazon) lens, but nothing in between. Panasonic offers a Leica-designed Summilux 25mm f/1.4, but that's more than three times the cost of the Sigma. And Voigtlander makes a low-light beast in the Nokton 25mm f/0.95, but it's manual focus only and $1,200. That makes this lens appealing if you're looking for something in this focal range on a budget, especially if you own an Olympus camera or the stabilized Panasonic GX7.

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