I purchased a 105mm DC lens recently and have been using it on a D40 and (with an adapter) on an Olympus E-1. While I've been generally happy with the lens, I've noticed a bit more chromatic aberration than I expected. It's most annoying when there's a high-contrast edge in a part of the image that is slightly out-of-focus. The aberration varies in color depending on whether the focus is slightly in front of or behind the edge. Focus in front produces a blue-green cast, and focus in back gives a red cast. The aberration is present even in the very center of the image, i.e., it's not just lateral chromatic aberration which could be easily corrected in post. The aberration is greatest at f/2 and gradually disappears as I stop down, though it's still noticeable in some photos at f/4. I haven't seen it in real photos at f/5.6, but then again I'm mostly interested in using the lens at f/2.8 and f/4, so I haven't taken many pictures with it at f/5.6. My question is whether or not this is normal behavior for this lens. If it's normal, I'll just deal with it in post as best I can, but if it's not, I'll send it to Nikon and see if they can fix it. I have created three montages that illustrate the issue, one at f/2, one at f/2.8, and one at f/4. These are using a black-and-white 2D test target so as to show the problem clearly. Each montage is a 3x3 arrangement of center crops taken with my D40. The rows correspond to slight front focus, in focus, and slight back focus, and the columns correspond to different settings of the DC control (neutral, rear, and front positions). For the rear and front DC settings, I used the position corresponding to the shooting aperture, e.g., R2.8 and F2.8 for the shots at f/2.8. Full-resolution montages are in my gallery. Here are reduced-size versions.