Pro Cameras » Discontinued cameras » GY-HM700/710/750/790

ID #1131

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:

  1. 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
  2. Zoom in on the chart in maximum telephoto and focus the lens with the normal (front) focus ring. 
  3. 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.
  4. Repeat steps 2 & 3 several times until both the telephoto and wide angle images are in focus.
  5. Tighten the thumbscrew being careful not to turn the macro ring.
The lens should retain its back focus during transport, and even after removal and reattaching.  However it's considered good practice to always check the backfocus before a shoot. 


Last update: 2009-06-22 14:29
Author: Dave Walton
Revision: 1.0

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