I'm looking for a wide angle lens for my Mamiya RB67 but having trouble deciding between the 50mm F4.5 Sekor-C, the 65mm F4.5 Sekor-C and the 65mm F4 K/L. I'm tempted to go with the order 50mm lens as I do appreciate it's very wide view, and my favorite lens on my Nikon is 24mm. But my favorite on my Hasselblad is a 60mm lens. That brings me to the choice between the older Sekor-C and the more modern K/L. From my research I get the impression that the 50mm is superlative, but that the 65mm K/L might be sharper than the other two. The Sekor-C lenses are also less money, but being older they may have problems that need attention. What to do?