Originally posted by lber I went through all my setting in the camera and under the menu in "Lens Correction" I had Lat-Chromatic-Ab Adj turned ON, turned it off and now it seem's a lot faster. What is Lat-Chromatic-Ab Adj mean? Anyone?
There are two types of chromatic aberration. Lateral means there is one colour fringed on the left of the object and its complementary colour on the right of the object. Some lenses show more of this than others and if you shoot raw you can edit it out in post processing. (The camera can also do some of this automatically if you have that setting turned on, but it takes processing power) It is better not to notice this CA, Pentax usually controls it well.
The other type is longitudinal, where the bokeh in front of the focus and behind the focus has a colour tint, usually one is purple and the other greenish. This is harder if not impossible to remove and Pentax lenses show this type more often. Well, all lenses can show CA sometimes, it just depends how much and under what conditions.
Purple fringing is slightly different - that is when dark objects in front of a bright background (like tree branches in front of a white sky) are coloured purple on the sides. This, too can be removed in post, especially if you shoot raw. It can be pretty annoying when shooting on overcast days. Cheaply-made lenses tend to show more CA and purple fringing, especially older ones.
Here is a nice article on this topic:
Chromatic aberration - Wikipedia, the free encyclopedia