In my quest for examples of all the cameras I've used over the years, I recently acquired a Petri Flex V. Hadn't seen one for nearly 40 years and the first thing that struck me was the quality of the construction -- heavy plating and outstanding covering. The shutter has a very solid reassuring sound to it. I traded off an Exa I to get my original Petri. The Petri had an instant return mirror and the Exa didn't. I didn't keep the Petri long because it had a proprietory lens mount and didn't have a meter. Later the company switched to the M42 screw mount. From what I can learn the Petri V was made from 1961 to 1964. The Petri had to be one of the best-made slrs of its era. They certainly don't me 'em like that anymore. I'll post a photo if anyone is interested.