I tried to use automatic lens cap LC-37C with 17mm F2.8 pancake. LC-37C is originally made for the use with new 14-42EZ. However, it works pretty well on 17mm pancake. I tried it, and it was really successful. It works pretty well, and it makes me love 17mm F2.8 again. When the camera is turned off, the cover stays closed. When the camera is turned on, the inner body of the lens slightly extends, and then it released the switches at two ears of lens cap, and as a result the cover of lens cap automatically opens. Side view. You can see the switch. It is depressed when the camera is turned off. "turned off" state. "turned on" state.