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Sharpness 
The Sony FE 28mm ƒ/2 offers decent results for sharpness when used wide open, but there's a great deal of improvement to be gained by stopping down. Corners are soft at ƒ/2, especially when mounted on an A7 body, but this is dramatically reduced by stopping down to just ƒ/2.8. The lens is better at ƒ/4 and reaches its peak sharpness at ƒ/5.6 - almost but not quite tack-sharp - where it remains until diffraction limiting starts to become a factor at ƒ/11. Sharpness is still good at ƒ/16, but degrades noticeably at the maximum aperture of ƒ/22.

Chromatic Aberration 
With in-camera CA adjustments enabled, the lens-camera combination does well to keep CA in check; it's prominent when used at wider apertures, but stopping down reduces it significantly. With the in-camera adjustments disabled, CA is quite prominent, appearing as magenta-cyan fringing in areas of high contrast.

Shading (''Vignetting'') 
When mounted on the sub-frame NEX series of camera, corner shading isn't that much of a big deal - extreme corners are only 2/3 of a stop darker than the enter of the frame. At any other aperture, it's a 1/4 stop darker.

Mounted on the full-frame A7 however, it's a much different story: when shot at ƒ/2, the extreme corners are 1 2/3 stops darker than the center of the frame. In-camera vignetting correction helps significantly with this. Stopping the camera down also reduces corner shading, with there being 1 stop differential at ƒ/2.8, and 3/4 of a stop at ƒ/4; at any other setting, you will see corners that are 2/3 of a stop darker than the center.

Distortion 
Distortion is quite a prominent factor for this lens, at least, with in-camera distortion correction disabled: we expect some level of barrel distortion from a wide-angle lens, but the lens produces some of the widest distortion results we've seen: +1.875% in the corners, when mounted on the A7. In-camera distortion correction is quite effective at curtailing distortion (just check our before & after sample images) and if you need to do it yourself in Photoshop, it's not complicated distortion.

Autofocus Operation 
The Sony 28mm FE ƒ/2 offers very fast autofocus performance. While the literature doesn't indicated that it's using the new Direct Drive SSM focusing system, it's said to use an "advanced linear actuator" that allows for quiet focusing. The lens took well under a second to rack from minimum focus distance to infinity. The quiet focusing performance should work very well for video recording.

The large focusing ring is an electronic focus-by-wire system, and switching into manual focus is controlled via the camera body itself since there is not a manual AF/MF switch on the lens. Also lacking on the 28mm ƒ/2, like most of Sony's other FE lenses, is any form of focus distance scale.

Macro 
The minimum focus distance for the FE 28mm ƒ/2 is just under 12 inches, which is very close a wide-angle lens such as this. It's not designed for macro photography, producing only a 0.13x / 1:7.7 magnification ratio.

Build Quality and Handling 
The 28mm ƒ/2 follows the same design aesthetic as Sony's other new lenses, with a sleek, matte black barrel design with modern, sharp edges. The lens barrel is constructed out of sturdy, solid-feeling metal. There are no external markings or features like a focus distance scale or AF/MF switch - the only thing on the lens other than the focusing ring is the lens' denomination - FE 2/28.

The inch-wide focus ring has many fine grooves, which provide an excellent feel and a secure grip. The focus system is all electronic, so the focus ring itself rotates continuously with no stops on either end. The rotational action is very smooth with just the right about of resistance for controllable and precise focus adjustments. Focus adjustments don't rotate the front element of the lens (and thus any attached 49mm filters), and since the lens employs internal focusing, the size of the lens doesn't change.

The ALC-SH112 lens hood ships with the lens - a petal-shaped, bayonet-mounted hood that adds about an inch to the lens' length when attached. It can be reversed and mounted for storage, and the interior is a matte black to help reduce lens flare.

Two adapters are available for the lens to offer extra wide-angle and fisheye capabilities: the SEL075UWC adapter widens the focal length to 21mm, while the SEL057FEC adapter widens the focal length to 16mm and provides a fisheye perspective. We didn't have either of the adapters for testing, but we can only assume that image quality will be slightly degraded when they are used.

Conclusion 
Sony's produced a nice optic in the form of the 28mm FE ƒ/2 - it hits a good price point for what you get, if you don't mind paying a slight premium for it. This wide-angle prime is compact, making it a great option for a small walkaround lens, plus the 28mm focal length is a great option for landscape and travel photography. With the bright f/2.0 aperture, the 28mm prime is also a great choice for low-light shooting.