While the original models came into the market in the 1970s, the SLR 680 was introduced in the 1980s and is the first and only folding SLR camera to both shoot 600 film, have a built-in flash and an autofocusing mechanism.  The autofocus mechanism (that big gold circle) uses actual sonar waves to focus on the subject matter, helping you get crisp photos each time. With the built-in flash, you can comfortably shoot in low-light environments. For a more hands-on approach, the autofocus mechanism and flash can be shut off.  The SLR 680s also feature the tripod mount and strap lugs found on Alpha and sonar models, making them the most versatile and decked-out of the Polaroid folding cameras.