Each year for the last 15 years, Robert Walker has stood on a 20-ft ladder -- and withstood rabbit ears, funny faces "and worse" -- to photograph graduating classes at the University of Arizona (UA) College of Optical Sciences, in Tucson. "You have to watch out for those things, to maintain order in the group," he said jovially from his home nearby. "I've sometimes had to yell at them." Somehow, they all muster the composure required for the brief exposures, though, as the 2007 class photos testify. Click on thumbnails for full versions.Insets from the University of Arizona College of Optical Sciences Class of 2007 photos. (Robert Walker, courtesy University of Arizona)"They all just love it -- some even come in costumes," Walker said. "It started out with 100 people 15 years ago, and now we have a bundle -- we're up to 250." The director of photograph services at the university for 25 years, Walker -- now "officially retired" -- is kept busy at his job, especially around this time of year. This is the first class photo taken in front of the new Optical Sciences Center building, which opened in 2006. The two views are for the benefit of the front and back covers of the center's annual yearbook. When the building was still an idea, Walker once posed the group around its architectural model. "When we did the back shot, we also turned the model around," he said.The subjects include students, faculty members and staff. One staff member, Information Specialist Coordinator Cathy Alexander, joked that the back view is incentive "to watch our weight." In the enlarged versions of the photos, Alexander is in the front row, next to the wall, wearing a black blouse and light pants. Robert Walker is not in the photos, of course -- "The poor soul is perched, with his camera, on a very tall ladder in front of us," Alexander said. "He always manages to get us organized with grace and patience." The UA College of Optical Sciences Class of '07 included a number of scholarship winners, among them Joshua T. Wiersma, the first recipient of a scholarship in memory of Jim Palmer, UA research professor emeritus of optical sciences, who died Jan. 4. For more information, visit: www.optics.arizona.edu/