Without such fine tuning, achieving high focus accuracy and precision is difficult. Many online articles, guides, and forum comments attest to the need to ‘calibrate’ or fine-tune the autofocus (AF) of lenses on a DSLR when using the viewfinder and phase-detection AF. Because Ricoh Imaging had released intermediate firmware versions, it is not possible to determine whether the substantive AFFA changes were introduced in FW v1.31 or in a previous version. It is possible that several minor AFFA changes reflect a margin of error in the test methodology, depth of field allowances, or tolerances in the camera's AF system. Notably, one lens, a DA 18-135mm, required a significant change in AFFA setting from minus 6 originally to plus 2 under FW 1.31. However, five of these lenses would have been at the margin of the acceptable range if their AFFA settings were not reset under FW 1.31.
Because of the inherent depth of field allowances under the test conditions, ten lenses would have been within an acceptable focus tolerance using the original AFFA settings under FW 1.01, although not necessarily optimal.
Using a repeatable quantitative methodology to calibrate the optimal AFFA settings, most of the eleven lenses in the procedure were found to require new AFFA settings for optimal AF performance. This article describes the changes in the Autofocus Fine Adjustment (AFFA) settings that were necessary after the author updated the firmware in a K-3 Mark III DSLR camera from version 1.01 to v1.31 in December 2021. It is believed that sufficient numbers of AFFA test runs were conducted to support a robust analysis.
It is possible that several minor AFFA changes could have been prompted by a margin of error in the test methodology, depth of field allowances, or tolerances in the camera's AF system.
Five settings would have been at the margins, i.e., just barely acceptable or slightly blurred. Notably, ten of the eleven lenses would have been within an acceptable focus tolerance using the original AFFA settings under FW 1.01, although not necessarily optimal. Edit: After further testing and analysis, some of the conclusions have been revised.
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