The three element lens on Yashica D is a Yashikor. The better four element lens is the Yashinon. Others say the Yashkor should be stopped down for best performance. The several Yashinons I've used have been fine performers. The Yashica TLRs may not be as reliable as a Rollie, but for the difference in price they are practical. Some of them do last. Decades ago I saw a Yashica A in Japan with severe brassing and the knurling worn down on the edges. It seemed to be in good condition except for the slowest shutter speeds.