I do not consider myself a photography techie, but I went through a process this past week that I found interesting.

I ordered a Sigma 50mm 1.4 Art Lens, and after I received it, I found a good number of articles and reviews suggesting that the lens’ autofocus needed to be calibrated using their special USB hub tool and special procedures for various distances.  After I began the process, I discovered I did not have the proper distance target for doing the calibrations.  So, since I was geared up for calibrating, I decided to calibrate it and all of my other lenses using Reikan Focal software (that had been sitting in my cabinet unopened) using the microadjustment function on my primary camera body. 

All of my lenses, except for the new Sigma, are Canon, some L and some standard.  Test results Focal reported included Lens Profile (showing the curves and locations of the sharpest microadjustment points), Focus Consistency, Astigmatism Factor and Front/Back Focus in which the Canon L lenses performed the best of the Canon as expected.  All of the Canon lenses required some autofocus adjustment, although none seemed very far out of whack.  The two standard prime lenses were the worst obtaining Result Confidences of “Poor”, and their curves were generally all over the place for the various attributes.  The generation III of 70-200 L was quite good from low to high focal lengths.  But, the most interesting result was that the Sigma lens required 0 autofocus adjustment at 99.9% Consistency of Focus.

Following is a summary of the autofocus microadjustments:

Darn the luck!  My go to 24-70 L V1 died on me this week, so I will have to recalibrate it after repair.  I discovered the failure was a known defect in the lens and unfortunately Canon factory no longer supported the older model.  I could have purchased the latest version but opted to send it to Royal Camera Service (www.royalcameras.com) for repair.  Their service was prompt and professional.  I have not yet given it a test run or calibrated it but am looking forward to it.  

I hope you photographers found this useful.

Bruce