Optical systems for linear lighting, particularly linear lighting that is installed in a channel, are disclosed, as are light fixtures that use these optical systems. The optical systems have multiple optical elements, usually a first lens adapted to be positioned close to a strip of linear lighting installed in a channel, and a second lens adapted to be positioned farther from the strip of linear lighting. In some cases, the first optical element may be a diffuser. The two optical elements are optically aligned with one another such that light from the first optical element reaches the second optical element. The multiple optical elements may be adapted to physically support one another, and to engage with structure provided by the channel for securing a cover. Some optical systems may be adapted to compensate for variations in the color or intensity of the emitted light.