Dark slide for changing lenses (right pic) A built-in dark slide curtain can be interposed between the lens and film when changing lenses to keep light from accidentally exposing film in the camera when the lens is removed. A safety interlock prevents removal of lenses unless dark slide curtain is employed. The curtain can be opened and closed using controls on the bottom of the camera. One-touch dark slide activation (left picture) An easy-grip knob allows easy activation, even while wearing gloves. Once a lens is attached, the dark slide can be removed simply by sliding the release.