Fovea

The fovea is the central focal point on the retina in the eye around which the cones cluster. In fact, the fovea has only cones around it, which are better for detecting fine detail. So, when trying to really see some fine detail or focus something, people tend to move the image onto the fovea (although they may be unaware that this is what they are doing...they just think they are trying to see something better).