Pop-out mobile cameras and actuators

A camera, comprising:

• a lens including a plurality of lens elements separated by air-gaps therebetween;
• an image sensor;
• a pop-out mechanism configured to control at least one air-gap between the lens elements or between a lens element and the image sensor, to bring the camera to an operative pop-out state and to a collapsed state;
• and
• a shape-memory alloy (SMA) actuator that includes two antagonistic SMA springs, each antagonistic SMA spring attached to two pins, wherein the two antagonistic SMA springs have the same thermal characteristics,
• wherein the SMA actuator is configured to move the pop-out mechanism to bring the camera to the operative pop-out state and to the collapsed state using the at least two antagonistic SMA springs and the attached pins by alternately activating the at least two antagonistic SMA springs.