Calibrate A Test Lens (new)

Calibrate a Test Lens


A basic fact:  The better your test lens, the easier it is to test and adjust autofocus.  So take some time and try to hand pick a high quality lens.  A Test Lens needs to be of good mechanical and optical quality.   You might even consider an image stabilizer lens.

Click here for TipsPicking A Test Lens


Points to Ponder:

  • Soft lenses lack a definitive point of focus.
  • Play in the focus threads will cause inconsistent focusing.  It can also broaden / soften the depth of focus.
  • The recommended lens is a 50mm F/1.8.
  • The recommended target distance is 1 meter / 3 feet.
  • SPT software allows to you calibrate more then one test lens.  You can shorten the distance to limit depth-of-focus.


Calibrating a Test Lens:

In our earlier software calibrating your test lenses determined the offset of the Zero focus point on the 3D target.

In this software version autofocus calibration is automated.  This requires using the software to build a Compensation Data file for your test lens.  As before you can create as many test lenses as like, building a separate Compensation file for each lens.

You start by manually focusing the lens to ‘zero’ on the 3D chart using the software’s Focus Viewer and focus tool to get exact focus. 


When ‘zero’ focus is achieved you tell the software by clicking the ‘yes’ button.  After that a series of flat targets are used to determine the phase shift of each set of AF sensor.  Clicking the ‘Start Phase’ button with each target / AF sensor line builds and finally creates the Compensation file.  

As you probably understand, the compensation data is the difference between true ‘zero’ focus and the AF phase shift.  

The ‘Help’ file and prompt windows included in the software gives you complete instructions.


To view Autofocus functions click on their Tabs Below:


Link to Previous Software Window

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