This is a Focal Length icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,900 icons, all in the same style and quality.
There is a single cone shape lying on it's side with the tip to the left and it's bottom face visible on the right side, beaming off the top and bottom of the bottom face is two diagonal lines, and halfway through each diagonal line is a curved line connecting them.