Involved in brassinosteroid biosynthesis (By similarity). Involved in internode elongation and seed development (By similarity). Catalyzes the conversion of campesterol (CR) to (22S)-22-hydroxycampesterol (22-OHCR, 22-hydroxyCR) (By similarity). campesterol + O2 + reduced [NADPH--hemoprotein reductase] = (22S)-22-hydroxycampesterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Plant hormone biosynthesis; brassinosteroid biosynthesis. Belongs to the cytochrome P450 family.