When you take a focus frame with the ARCON software at WIYN, you typically take a short (3-10 sec) exposure of a 11-12th mag star, clock the charge down 30 rows, decrease the focus value, take another exposure, clock down the charge, decrease the focus, etc., for a series of 7--9 exposures. The frame is then read down, the the image examined with mscfocus to determine the best focus value. Note that the double-space gap occurs after the first exposure. A sample run is shown in Figure 8.