Digital Cinematography, 2nd Edition

Lenses 147

misleading, MTF graphs include multiple data

points along the diagonal from the center of the

frame to the corners of the frame. When optical

technicians test MTF, they generally rotate the

lens through 360 degrees, and the measured MTF

at the edge of frame is taken as an average.

Figure 7.10 Measuring lens MTF.

Lens MTF is evaluated using square wave grid

patterns, evenly spaced black and white lines at

two sizes, 10 lines/mm, and 30 lines/mm. There

are two groups of data plotted on an MTF

chart,Sagital and Meridonial lines. The Sagital

lines are the pairs of lines that run along ...