michael_tennant

<p>Boy, those are some great responses! Gentleman, thank you very, very much for contributing. Ilkka, I read another one of your posts about AF Fine Tune, and had hoped you'd have thoughts about this. (I did my testing at about four and a half feet. I should have mentioned that in the first post.)</p> <p>Rodeo Joe, I have a feeling you nailed the issue right on the head. The example cited at the bottom of the linked page is convincing. (Convincing and a little amazing; I'd never guessed stopping down could have that much of an effect.)</p> <p>Looks like I'm in for another session with LensAlign.</p> <h1> </h1>

<p>I should have mentioned this article, too:</p> <p>http://www.dslrbodies.com/newsviews/nikon-focus-followup.html</p> <p> </p>

<p>After spending most of the morning fiddling with my D4S, LensAlign and two Nikon lenses, I thought I was getting consistent results. Specifying an AF Fine Tune of +3 for the AF-S 50 1.4G produced spot on focus on the 0 mark on the LensAlign ruler. The AF-S 24-70 f/2.8 zoom was tougher to calibrate, but specifying an AF Fine Tune of +10 put me spot on at 60mm and slightly front focused at 28mm.</p> <p>I took many shots with these +3 and +10 figures, saw consistent results, and figured I had successfully configured AF Fine Tune. I did my experimenting during the day in diffuse natural light, at F8 (as Michael Tapes suggested for LensAlign, or at least my version of LensAlign). I set up the LensAlign carefully, to center the red LensAlign 'bullseye,' defocused the lenses between shots and made sure to take test shots with the LensAlign sight gate closed. </p> <p>This evening, I slipped on an SB-900 flash and took some casual snaps in my living room of a telescope with a long line of embossed letters on the telescope shaft. I'd just calibrated my lenses with AF Fine Tune, and figured I'd nail focus at the aimed-for letter with both 1.4 on the AF-S 50 and 2.8 on the 24-70. This time, though, I was hand holding the camera at 1/60 or 1/80, shooting with iTTL flash and shooting with the lenses wide open at 1.4 and 2.8, respectively, rather than F8. </p> <p>Well, I <strong>didn't</strong> nail focus. The 24-70 came close, but the AF-S 50 1.4G didn't consistently focus on the money until I changed the +3 (for mild front focus) to -20 (!!) for severe back focus. </p> <p>I'm nearly new to AF Fine Tune. (As you can probably tell.) I could load some shots into Photoshop, draw in little arrows to show what I was trying to focus on and so forth, but would rather just hear some off-the-cuff thoughts from those more experienced than I am with Fine Tune. Does this post make you think "equipment problem," or have you seen similar variations in different lighting situations, particularly when shooting wide open with a lens as fast as the 1.4? </p> <p>(Or, maybe I'm trusting those Nikon focus points more than I should, if this vintage Luminous Landscape article still holds today: http://www.luminous-landscape.com/tutorials/nikon-focus.shtml )</p> <p> </p>