Does the back focus have to be set every time the lens and body are removed? What is the procedure for setting the back focus?
The back focus procedure may vary slightly from lens to lens.
Generally, the procedure is this:
- Shoot a resolution chart (radial type preferred) with the aperture wide open. You can accomplish this by reducing illumination, adding ND filter, or applying faster shutter speed. Aperture should be wide open for the most accurate adjustment
- Zoom in on the chart in maximum telephoto and focus the lens with the normal (front) focus ring.
- Then zoom out to widest angle. Loosen the
thumb set screw on lens MACRO adjustment ring. Focus the camera at the
wide angle using the MACRO ring.
- Repeat steps 2 & 3 several times until both the telephoto and wide angle images are in focus.
- Tighten the thumbscrew being careful not to turn the macro ring.
Last update: 2009-06-22 14:29
Author: Dave Walton