Volume holograms may be used to make rejection filters which have narrow spectral bandwidths. A unique, and potentially useful, feature of such holographic filters is that the reflecting planes (Bragg planes) need not be parallel to the substrate. For example, spherical holograms (holograms of a spherical mirror) can be made on flat substrates. The slant angle, defined as the angle between the Bragg planes and the substrate, in this case will increase continuously from the center of the hologram to the edge. It has been observed, however, that when such holograms are made in the DuPont photopolymers the playback wavelength is a function of the slant angle. Under identical exposure and processing conditions the playback wavelength increases with increasing slant angle. The degree of shift with slant angle is affected by the presence and type of cover film or cover material used to protect the photopolymer during exposure and processing. In addition to the anomalous spectral shift, the line shape of the reflection band is distorted and the distortion is a function of the playback angle. The results of the experimental observations are reported and discussed.