
52 Image Processing for Cinema
FIGURE 2.32: Diagram of a simple zoom lens. Figure from [21].
of focal lengths the zoom lens works with, zoom lenses with ratios above 3x
produce images of lesser quality than prime lenses. This is mainly an issue in
still photography because image defects are less visible with moving images
and lower resolutions, as in TV [21].
2.6.4 Modulation transfer function
The modulation transfer function (MTF) of a lens measures its capability
to transfer detail from object to image. Transfer functions characterize sys-
tems that produce an output given an input. In an optical system, detail is
given by the resolution, usually