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.
