Cheng submitted "Flying Creatures" for his master's, which was rejected at first but later accepted after winning public acclaim. Later, older and wiser, he first exhibited another selection of his photographs, "Contemporary Photography," before trying for his doctorate, a title he won easily.
不管如何，鄭桑溪還是認為他的碩學、博學資格是靠實力贏來的，倍覺珍貴；不像後來，有些人可以利用其他管道，輕易地取得榮銜，方便他的社會行為，而與真正的「攝影」無益又無緣，徒增笑話與糾紛罷了。