The Influence of Image Motion and Shutter Operation on the Photographic Transfer Function

In Part I a general two-dimensional expression for the transfer function of the photographic exposure image is derived, including as factors the optical transfer function, the transfer function arising from scattering of light in the emulsion, the shutter function, and the motion of the image. The effect of shutter operation in the absence of image motion is discussed and it is shown that a focal-plane shutter acts as an independent agent with its own effective transfer function, whereas a between-the-lens shutter is not independent but acts as an apodizing agent. In Part II, the effect of image motion is discussed, with the assumption that the optical transfer function is independent of the shutter action. The concept of an equivalent spread function for image motion is developed, and uniform linear image motion and harmonic image motion are discussed in detail, the latter especially for the case where there are at simple the most only a few periods in the exposure time. An approximation for small degradations is then obtained in which all possible combinations of uniform linear motion and simple harmonic motion are contained. Throughout the paper the functions discussed are functions of two-dimensional space.