Yes, most definitely.<br>I have done field work for years as an archaeologist, and "eyeball calibration" is definitely an important factor. I think it a matter of concentration and mind set, once you have learned to recognize what items are significant in your search. I try to speed up the adustment period by reminding myself to concentrate on locating shells, pottery sherds, etc. and focusing on the business at hand. It still takes time to happen, so you may need to discard or review the first fifteen minutes of effort.<br><br>I volunteered for several years in mountain search and rescue, where the same eye ball calibration must occur for effective work. You need to find footprints, dropped items, broken vegetation, and the like. I knew I was calibrated when I was noticing archeological material.<br><br>Fatigue and time reduce calibration; I tapered off a lot around 3AM.