I haven't used SX-70 film in years. I remember back in the days of Polaroid instant film it had a certain level of popularity due to the fact that you could manipulate the emulsion right on the print as it developed, giving the final image a sort of painterly look. Honestly, I always found that technique a bit hokey, however I have long admired the color pallet of SX-70 film and really lamented its loss when Polaroid closed up shop. Thankfully now days the Impossible Project stock delivers pretty good (though very expensive) results.
On a whim I decided to pick up an old SX-70 camera with autofocus. Polaroid was always a company that thought outside the box and it was no different with their autofocus system, which actually works on sonar. Yup...sonar. When the shutter button is pressed halfway, a series of ultrasonic chirps is emitted from an electrostatic transducer located under a plate over the lens. These chirps travel to the subject and bounce back to the camera’s receiver, alerting the camera to the subject’s distance, and the lens is turned on a motor to focus accordingly.
Really damn cool...