The sub-pixel group 132-3 may include 16 sub-pixels SP (4×4 sub-pixels SP) as described with reference to FIG. 3. Each of the sub-pixels SP may include two photoelectric conversion elements. For example, a first sub-pixel SP1 may include a first photoelectric conversion element PD1 and a second photoelectric conversion element PD2, and a second sub-pixel SP2 may include a third photoelectric conversion element PD3 and a fourth photoelectric conversion element PD4. A third sub-pixel SP3 may include a fifth photoelectric conversion element PD5 and a sixth photoelectric conversion element PD6, and a fourth sub-pixel SP4 may include a seventh photoelectric conversion element PD7 and an eighth photoelectric conversion element PD8. In this case, each of the first to eighth photoelectric conversion elements PD1 to PD8 may convert a light signal converged through the corresponding color filter into an electrical signal. Operations of sub-pixels SP that are not illustrated in FIG. 7 may be similar to operations of the first and fourth sub-pixels SP1 to SP4.

The diameter d3 of the micro lens 131-3 may be determined based on the corresponding sub-pixel group 132-3. For example, the diameter d3 of the micro lens 131-3 may be the same as a total width or depth length of the first sub-pixel SP1, the second sub-pixel SP2, the third sub-pixel SP3, and the fourth sub-pixel SP4.