[en] In charge uncompensated Ca_X:YIG, magnetic anomalies and a photoinduced absorption spectrum have been reported. The temperature dependence of the photoinduced peak observed at 1.85 eV (width 0.5 eV) has the same temperature dependence as the low-temperature anomalies observed in the magnetizations. A model to explain the low-temperature magnetic anomaly assumes that a non-S state iron ion, Fe⁴⁺, is created in the tetrahedral site that is ferromagnetically coupled to the octahedral Fe³⁺ ion. An alternative model recently proposed assumes that O^- ions are formed which would influence the magnetic properties in similar fashion. The broad nature of the absorption at 1.85 eV is characteristic of a resonant transition of photocarriers. In this paper the absorption band is discussed in terms of a polaron hopping model