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| p.7 #8 · DotTune: New AF tune technique, no photos required |
This is actually an inferior technique as it relies on the small LCD to determine whether a small object is in focus.
I am shooting with lens with focal lengths of 200mm up to 1000mm (with teleconverters) and use a test object that is at a distance of 200 feet and is 3 x 6 inches in size with stamped lettering into metal. I can tell in the images the level of sharpness both closer and further from the test object and also determine the sharpness of the embossed lettering as a 3-D test subject.
I need to view the test shots on a computer monitor to compare slight differences in sharpness between the different AF Fine Tune settings.
I take successive shots at -5, 0, +5, +10, +15 which takes less than a minute to do. I then look at the pictures and determine which setting provides the sharpest rendition of the test subject. If it is -5 then I take a series with -5, -10, -15 and review them. If it is the +10 with +15 the next best then I take a series at +10, +12, +13 and compare them to get it dialed in. This entire process takes 5 minutes but it is a one time test.
The reality is that when I travel to a distant location and in theory should redo the test on the lens with the three teleconverters I am not going to try to find a suitable test subject at a suitable distance and repeat the testing with my laptop.
It took me less than an hour to test my new 500mm f4 with the three Nikon teleconverters with my D800e and D7100 cameras and produce AF Fine Tune settings. I see no reason to go with a less accurate process that is not likely to save me time and even if it did a difference of minutes is inconsequential in the overall scheme of things.
I believe based on my experience with Nikon and Canon telephoto lenses that the AF fine tune adjustment needs to be for the greatest expected focus distance and not for something that is 30 feet away which is why I found the AF targets useless for fine tuning purposes with any of my telephoto lenses.