People complain about the lens distortion at the widest viewing point on the Sony E-mount 18-55mm lens. But these are the types of people who usually don't know how to use a lens that has been designed to incorporate the broadest range of shooting styles. At 18mm the SEL 18-55mm does exhibit some slight image curvature,(obviously nowhere as much as an actual fish eye lens) however for the types of pictures that many people want to take, it often helps create more of a dramatic visual effect when used on spaces (with or without a subject placed at the centre) and on architecture. There once used to be a time where people would go out of their way to get lenses that would create this slight effect despite not knowing that it was these slights of specific distortion that caused it.

At about 27/28mm the barrel distortion is less apparent.

At about 50 to 55mm its even less so.

Even at 50 to 55mm camera shake shouldn't really be a problem because the NEX camera is so damn light. But even if it is the image stabalisation should more then help when shooting at 50 to 55mm. 

50 to 55mm is also ideal for less distorted portrait snaps.

If you're really serious about minimising lens distortion to avoid funny shaped looking heads for portrait snaps you'll need a different type of lens altogether, and the pursuit of minimal image distortion for portraits through default physical optical properties with the least amount of software correction doesn't come cheap either. 

Funnily enough, I reckon a large amount of this would also apply to the Canon 18-55mm lens for canon crop sensor camera's too.

But even if you use what I've written here as a general guidelines for taking better snaps within the limitations of an 18-55mm lens, there will still be some distortion present at 50 to 55mm. It might also be the case that you want an even lesser degree of lens distortion, say for more scientific based application or for quantity surveying (but I would have thought in such instances the necessary equipment would have been provided to begin with), or for more general applications, you maybe just want to stop someones head from looking a funny shape in certain pictures. Whatever the case in such instances, Adobe Photoshop will prove to be an essential tool which I'll cover in another part.