Camera Repairer how-to

How to Diagnose a Lens Autofocus Problem

Focus errors have many causes.

Updated By the Career Education Institute Curriculum Team
Quick answer

Focus errors have many causes. In short: shoot; check; test, then complete the remaining steps below.

Step by step

  1. Shoot a test chart.

  2. Check front or back focus.

  3. Test on another body.

  4. Check contacts.

  5. Calibrate.

  6. Retest.

Safety reminders for camera repairers

  • Use ESD protection
  • Handle flash capacitors carefully
  • Protect eyes
  • Ventilate cleaning solvents

Sensor · Shutter · Aperture · Autofocus · Collimator · Front focus: see the full camera repairer glossary.

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