The dynamic viscoelasticity and birefringence of well-characterized semiflexible polymer solutions-cellulose tris(phenyl carbamate)/tricresyl phosphate solutions-were investigated over a wide concentration region ranging from a dilute to a tightly entangled regime where the entanglement spacing is smaller than the Kuhn segment size. The stress optical rule did not hold true in the tightly entangled regime, indicating that the molecular origin of stress is not simply attributed to the orientation of segments but to the bending of chains, which does not contribute to birefringence significantly. At high frequencies, the power law behavior with the exponent 3/4 due to the tension stress was observed for the complex shear moduli at all the concentrations.