SineImage YE0220 Back Focus Test Chart for Camera Lenses
| Material | Film or HD photographic paper |
The Sineimage YE0220 back focus test chart is designed for
adjustment of camera lenses and checking back focal distance. It
consists of a large Siemens star in the center an four smaller ones
positioned in the corners of the test chart.
With the aid of a low transmission filter and by means of low level
lighting make sure that the camera is not over modulated with the
aperture in the open position.
a) Optical focus: Adjust focus at shortest focal length.
b) Back focal distance (lens): Adjust focus at shortest focal
length by regulating lens mechanically with adjustment screw and
optimize alternatively with a).
c) Back focal distance (pick-up tubes): If focus varies from
channel to channel between greatest and shortest focal length, the
individual pick-up tubes must be adjusted mechanically in the
optical axis.
1. Select white channel. Set optical focus at greatest focal
length. With shortest focal length and divergent f ocus adjust the
pick-up tube in W-channel until optimum focus is achieved. If
necessary optimize by alternating with optical focus adjustment.
2. With unchanged optical focus adjustment and shortest focal
length adjust the red and blue pick-up tube until optimum focus is
achieved. Image focus (focus adjustment) is maintained at all focal
lengths (zoomin) and constant distance from object by means of back
focal distance adjustment.
