EXCERPT page containing first few paragraphs. 2024-04-18 09:11:31
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SD1 Autofocus Errors
The SD1 Merrill gave me a terrible time in terms of focus; most of the material shot with it was out of focus and with both lenses. Sigma told me that camera was “working fine” when shipped to me. But as seen with Nikon gear, “in spec” can nonetheless mean problematic.
This page shows the consistently severe backfocus error.
Preface
The test gear came directly from Sigma, and I did not go about calibrating the system. Calibration takes considerable time and effort, the best tool being LensAlign, and in the end it is a precision that is the issue, as past testing with Nikon has shown, and precision cannot be fixed by calibration (with any brand). That is by definition, using 'precision' in its true meaning. The best one can hope for is centering the scattershot pattern more evenly around the desired focus point, in an average sense, aka accuracy.
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Sigma SD1 Merrill + Sigma 18-35mm f/1.8