The visual-resolution characteristics of an array, comprising many elemental afocal optical units, for an optical viewer are investigated. First, it is confirmed by wave optics that lightwaves exiting the array will converge, forming a three-dimensional optical image. Next, it is shown that the convergence point and resolution characteristics depend on the angular magnification of the afocal unit. When the magnification is 1.0, the lightwaves focus on the convergence point, and the resolution characteristics depend only on the diffraction of the afocal units. At magnifications other than 1.0, the lightwaves do not focus on the convergence point, decreasing the resolution as a result. To clarify this result quantitatively, we determined the viewing distances at which the alignment of the afocal units is not perceptible when an optical image formed by the array is viewed by an observer, and we calculated the modulation transfer functions normalized by the viewing distance.