Darin McQuoid Photography

Sony NEX-5N and Chromatic Abberations

Wiki is better able to explain CA's than I am. On the NEX-5N chromatic abberations, or perhaps internal lens flare, can strike a vengeance. I won't postulate on why it's happening, as it could one or a combination of many issues. What is happening is that ugly fringing and or loss of contrast happens while shooting high contrast scenes with any lens shot at maximum aperture while the electronic first curtain shutter is enabled. The electronic front curtain shutter is enabled when the camera is new or reset to factory default. What makes it more confusing to deal with is that Sony ignores "electronic" when they label the feature in the menu.
In short, unless at a critical shutter speed where vibration is a concern, or a 10fps burst is desperately needed, the feature is best turned off, and the camera will use a mechanical front curtain shutter.

To do so:
Menu -> Setup -> Front Curtain Shutter -> Off

Here are two very unexciting images illustrating the issue. It was a rather overcast day, the higher the contrast the worse the results. The issue is exacerbated in older lenses like the Nikon 75-150 f3.5 Series E, used here.

Electronic Front Curtain Shutter On

Electronic Front Curtain Shutter Off

How about in the real world? At first glance this image doesn't look too soft.

Sony NEX-5N and Nikon 75-150 f/3.5 @ 1/800 f/3.5 ISO 100

A 100% crop shows massive CA and overall loss of contrast in a scene that had good light, note the CA in the water at the paddle blade.