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| p.2 #19 · p.2 #19 · DotTune: New AF tune technique, no photos required |
I am very confused trying to do this. What am I doing wrong?
I go into live view and focus. Then I switch the camera to viewfinder view and turn off the auto focus. I don't see any difference in the green focus confirmation dot no matter WHERE I set the micro adjust to.
I've seen this with my D800 when I was DotTuning my Sigma 35/1.4.
What I did instead of switching the lens into manual focus mode or the body or both was to set AF to AF ON only rather than AF on the half-press of the shutter.
Focus in live view via AF-ON (or manual focus); turn live view off, depress shutter to the half-view, adjust AF Tune, repeat as necessary.
Does DotTune work? I've checked out two lenses that I extensively profiled using software and to my satisfaction can state that the DotTune method gives me excellent results that are consistent with a software analysed tune. What's more... you can do it anywhere, in the field, if necessary, no laptop necessary, no software, no pre-printed target even if in a pinch.
I'd purchased a discounted copy of Reikan FoCal Pro a few weeks ago when I got my Siggy 35/1.4 and through much testing with it, determined that there is definitely something of a bell-shaped curve for optimum tune results. FoCal has an AF tune consistency function which plots quality of focus per exposure and in addition allows for multiple exposures at each AF Tune value. What becomes obvious when you see the results plotted on a chart that the highest quality of focus does not necessarily coincide with the most consistent focus. A tightly grouped cluster of plot values with no anomalies sitting way out there is the ideal, and often this ideal would be at an AF Tune value that didn't necessarily deliver the absolute maximum focus quality.
When I ran FoCal Pro against my Sigma, the peak of the bell curve / most consistent result suggested AF Tune of -7 or -6. DotTune came back with -7 or -6 the first time I did the exercise in less than ideal lighting, -7 or -8 when I used a chair with a patterned fabric as the target, and -7 or -8 in ideal lighting with a high contrast AF test target.
So I've used -7, made a number of close in to infinity exposures, and am very happy with the consistency and quality of focus.
Costs nothing but some time to try; if you are considering buying AF tuning software I'd suggest going through the DotTune process first.
Your mileage may vary. Past results are no guarantee of future performance. Warning, continued use may result in the growth of a leathery tail.