davood_rafiei

<p>I did send the lens to Nikon since it was under warranty, and it came back yesterday. The invoice indicates that the helcoid is replaced. I have been playing with it for the past hour or so and the auto-focus issue appears to be fixed (or at least the lens passes the test I set earlier). </p>

<p>Thanks Nick, for the test. This confirms my suspicion that my lens may need a trip to the Nikon service.</p>

<p>Thanks everyone for all the comments. However, the main question here is not addressed. The question is not how one should focus in close distances and whether to use manual or autofocus. Let's treat this lens as a short telephoto (and not a micro). The question is how the autofocus on this lens is expected to perform (say on the test given above). This will help me clear out if there is a defect in my copy.</p>

The lens is the current AF-S VR G model (and the camera is D7100).

<p>The above test should be done with the camera focus set to AF-c, allowing the camera refocus.</p>

<p>The problem is not just with subjects at close distances but is general. The DOF cannot be an issue if I am comparing the lens to Nikon 70-200, f/2.8 with the zoom fixed at 105mm and the aperture at f/2.8. Since I have had the lens used, I am not sure if this is a problem with my copy in particular or something that is expected of this lens. Perhaps those who own this lens can answer this. <strong>Here is the test</strong>: <em>keep the shutter half-pressed while moving the camera on different directions; is the AF engaged as the camera moves between subjects at different distances?</em></p>

<p>The lens is functioning flawlessly and is taking great pictures (<a href=" sample</a>) except the auto-focus component which seems slow and acting a bit strangely (or at least different than all my other nikon lenses). In particular, in continuous-servo AF (AF-c), all my other lenses keep refocussing when the shutter is half-pressed and the camera is moving between subjects; this is not happening with this micro lens and I have to keep releasing the shutter and half-pressing it again. Also sometimes the shutter must be half-pressed multiple times to get the focus right. I wonder if anyone has experienced a similar problem with this or other Nikon lenses, or have a solution?<br> It should be noted that the camera/lens contacts are cleaned regularly and cannot be an issue. Thanks.</p>