Wednesday, 25 January 2012

Lens Sharpness Test

Preparation and Settings:

  • Clean the Lens
  • Put the camera and lens on a tripod
  • Remove the glass filter
  • Attach the lens hood
  • Turn the camera on
  • Set the lens' autofocus drive for M/A, A, or AF
  • Turn the lens' VR OFF
  • Set for Single Point AF
  • Set for AF-Continuous Servo AF (AF-C)
  • Shoot at RAW Uncompressed (or Lossless compressed) and 14-bit (if available)
  • Turn Active D-Lighting OFF (if available)
  • Turn Long exp. NR OFF (if available)
  • Turn High ISO NR OFF (if available)
  • Set AF-C Priority Selection (in a Autofocus menu) for Focus (if available)
  • Set Focus Tracking with Lock-On to OFF (if available)
  • Set Self-Timer Delay (in c Timers / AE Lock menu) to 10s
  • Set Exposure Delay Mode (in d Shooting/display menu) to ON (if available)
  • Set for the LOWEST Base ISO sensitivity
  • Manual mode
  • Set the aperture for the highest aperture
  • Adjust the shutter speed until meter reads "0"
  • Place the aluminum soda can (e.g. Coke) dead in the center


Shooting:
  • Use Remote Cable and Mirror Up (Mup) to shoot (add the sandbeg onto top of the camera on its axis, if available, before shooting)
  • Repeat the steps for all apertures from maxumum aperture (lowest f/number) to minimum aperture (highest f/number), differing by one full stop (e.g. 1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11.0, 16.0, 22.0)
  • If you wish to test a zoom (changeable focal length) lens, do full test for the widest focal length, medium focal length, and narrowest focal length (e.g. on the 24-70mm lens, test at all appertures at 24mm, 50mm and 70mm).
Inspection:

From the Lens Sharpness Chart, find the focal length(s) and aperture(s) your lens will be normally sharp.

Use one of the RAW development softwares (Photoshop, Lightroom, etc.)
  • Import the images into LR, 
  • Click on Develop tab to start developing and scroll down to the Detail section
  • Set the Amount for 75%
  • Set the Detail for 50%
  • Go to the last image on the filmstrip then press and hold Shift then click on the last image (selecting all images)
  • Click on Sync then ensure all boxes are checked
  • Click Synchronize
  • Go back and click on the first image
  • Click on the main preview for 100% magnification
  • Inspect only in the dead center (the can) of the image
  • Check the softness of all images (and compare the Lens Sharpness Chart)
Next Stpes:
  • If the lens suffering some softness, run the tests again.
  • If you lens continues to suffer from softness, proceed to AF Fine Tuning to calibrate the lens for improved sharpness performance.









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