I just bought a TTL prism finder from KEH for my P67. It uses the camera's battery rather than one of its own. I've gone through four batteries with it almost immediately. The batteries were 4SR44 silver oxide. I've had them in my bag for a while, but I can't believe they're so expired that they drained almost immediately. Is the TTL prism the culprit? Do people who use this prism turn it off almost immediately after metering? Should I be using a different battery? Will the world end in December? Will I win the lottery? Any help with the camera questions would be appreciated very much...the other two....well....you probably don't know either!