Welcome to our Technical Information Pages!
Understanding Focus Compensation
  • Would it be correct to say it is basically not possible to get 100% AF focus, only very close because of some mechanical and maybe optical tolerances?”  Peter / Accurate Instrument Servicing Pty Ltd




Most lenses aren't made accurately enough to focus perfectly, but they should back or front focus consistently. So a lens contains a data file called ‘Focus Compensation’ which tells the camera body how much the lens back or front focuses.



  • Lens Focus Compensation:
The purpose of Lens Focus Compensation is to make the lens give the best focus for all cameras. It assumes the Camera Body AF systems are in good calibration.  
This is not an AF adjustment, Lens Focus Compensation is used by the camera body as part of its AF calculations.



  • Technical Information:
  • Lens Focus Compensation is only calibrated for the central AF frame in the view finder
  • It has separate calibration values for different types of AF sensor in the central frame
  • It has separate values for different zoom settings
  • It has separate calibration sets for different EOS  AF Systems



Canon Lens Professional Software:

  • Help / Using the software / Lens Operations Menu / Focus Compensation-Adjustment Overview

Japanese IS Part Label

The left hand kanji loosely translates as "Medium" and that the right hand one translates as "Feeling".

  • Left set is IS Central Position 
  • Right set is IS Shift. 




Central position values tend to be near zero (E1 = -31 and E9 = -23 in decimal) and IS Shift values tend to be midway between 0 and 255 (7B = 123 in decimal). 



So the typical values in the photo above are:

  • Left = IS Central Position 
  • Right = IS Shift


Some lenses have IS Lables with eight figures to enter for IS Shift and Gyro rank, while others have only two. 




The IS Lable above is for the 'EF-S 18-200mm F3.5-5.6 IS' which doesn't have a gyro rack so:


  • Left column = Pitch and Yaw for IS Central Position
  • Right column (with the four figures) = Pitch and Yaw for IS Shift


George Barroso / FantasTEC Photo Service:


“The IS setting label provided with the Canon replacement part, made perfect sense once I was in the software. 


Its all there, very easy and all alignments fell right in. Testing the lens after the repair (new IS unit) and alignment was perfect.”

Canon Lens Plugin Purchase Details

Purchase Details

  1. Connect your Lens to your PC, through a compatible Body.
  2. Connect your Lens to the Software.
  3. Click 'Connect' -- if the Lens Plugin is not installed, you will get an alert
  4. Purchase the Plugin and wait for your ‘Plugin Confirmation Email’ from SPT.(Your Invoice is NOT the Confirmation Email)
  5. Relaunch your software and click:  ‘Connect’ / ‘OK / Install or Install All (for multiple Lens Plugins).

The Effects of Lens Release Dates and Firmware Versions!

The Effects of Lens Release Dates and Firmware Versions!


Older Lens and Firmware versions have fewer Supported Operations - allot fewer!  SPT Canon Lens Professional software always uses ‘ALL’ Operations that the Lens and Firmware supports.



Canon Lens Interactive Software

SPT’s Canon Lens Interactive Software


Outwardly two same model Canon lenses may look identical, but variations in manufacturing dates, firmware, etc. can make them very different lens to service.  


Canon Lens Professional and its Plugins automatically synchronize its Supported Operations, Adjustment Menus and Service Methods specifically to the Canon Lens being serviced!

Here are two Canon Lenses both equipped with IS and USM:

Although we are only showing the Supported Operations Menu changes extend throughout the software;  including differences in Adjustment Menus, Service Methods and even the directions in the SideBar window.  



Not all USM lenses allow adjustment (Automatic or Otherwise).  There are various different reasons - some are too early, while others, like the above example, have inbuilt self-calibration. 


SPT’s Interactive Lens Software makes your job easier!