I will try to explain this the best way I can.
I have a D5000 and I just started experiencing a very annoying problem. With the standard included lens, Nikon DX 18-55mm, it will not autofocus at the 18mm "setting" on an object more than 10 feet away or so. It WILL AF on an object closer than about 10 feet or so on the 18mm setting.
Example, if I want to take a picture of the house across the street and go wide on the lens (18mm), it will not focus and therefore not allow shutter release. Now, if I turn around and want to take a photo of my garage door 5 feet away at widest (18mm), it will focus and allow shutter release.
Now...in Live View (LV), it WILL focus on that house in my example!!
So, AF works in LV but not through the view finder at the widest setting.
I reset the camera per Nikon instructions, and the A/M button is on AF and there is plenty of light and contrast.
PLEASE someone...through me a line!
#1. "RE: D5000 focusing issues" | In response to Reply # 0Wed 13-Oct-10 11:10 AM | edited Wed 13-Oct-10 12:10 PM by Covey22
You need to baseline your autofocus servo and area modes in order to troubleshoot.
Pick a standard Shooting Mode - say Program (P).
Select AF-S (Single-servo AF) Focus Mode. This locks the shutter until focus is obtained. Perfect for stationary subjects.
Choose Single Point AF-area Mode. This makes all 11 focus points individually accessible to you during shooting by using the multi-selector.
When composing in the viewfinder, use the multi-selector and pick the center-most focus point in the array.
Note that your subject must have good contrast, illumination and lines/angles allowing the AF system to work properly.
Zoom out to your preferred focal length. Overlay that center focus point on your subject and half-press the shutter to activate AF. In the viewfinder you should see focus achieved and the Green AF confirmation light illuminated. Fully depress the shutter button to take the photo.
This is the most simplest of settings and forces the camera to fully achieve focus before firing the shutter (focus priority).
Is this what happens or is something else occurring? If so, where do things start to deviate?
#2. "RE: D5000 focusing issues" | In response to Reply # 1Wed 13-Oct-10 02:00 PM
I did this and at full wide, still nothing. What I did do is hold down the shutter release 1/2 way and slowly zoomed in from 18mm...only when I got to about 30mm or so did the camera focus and I got the green light.
#3. "RE: D5000 focusing issues" | In response to Reply # 2Wed 13-Oct-10 02:40 PM
A couple of things:
1. Can you post a photo of what worked at 30mm when it locked on? I'm curious to see what the subject looks like overall.
2. Try a different subject, same range. Set it up yourself, preferably outside so the indoor illumination is not a factor, say - a chair at 10+ feet away in the middle of a lawn - there's very little that it will mistakenly lock on to or have problems identifying that the chair is the subject of interest.
3. If you override the lens and manually focus, can you get the green AF light? You may need to turn the focus ring slowly in increments.
#4. "RE: D5000 focusing issues" | In response to Reply # 3Wed 13-Oct-10 03:35 PM
3.) I used the manual focus and at the same distant object at wide, it indicates focus (AF green light). Go back to AF on the exact same object and the exact same distance...no AF, no AF light.
#5. "RE: D5000 focusing issues" | In response to Reply # 4Wed 13-Oct-10 03:58 PM
Did it ever work at all? I understand from your original post that it started happening recently, but it's useful to understand if it ever worked properly to begin with.
My initial thoughts is that there is a characteristic of the subject that is not playing well with the phase detect system - so it's one or more of those rules; angles, lines, color, contrast, illumination - that is not being met.
The other thing I should mention is that you should try to make sure that the subject under the focus bracket exceeds the size of the bracket as displayed in the viewfinder. The correlation is not 100% accurate; the actual autofocus sensor points could be slightly offset from the bracket's notation on the VF, but it's another good rule of thumb.
Something else to consider - you may have seen this in your lens' manual depending on whether you own the 18-55 or 18-55 VR.
Notes on using wide or super-wide angle AF Nikkor lenses
In the following situations, autofocus may not perform as expected when shooting with wide or super-wide angle
AF Nikkor lenses.
1. When the main subject in the focus brackets is relatively small
When a person standing in front of a distant background is placed within the focus brackets, as shown in Fig. E, the background may be in focus, while the subject is out of focus.
2. When the main subject is a finely patterned subject or scene
When the subject is finely patterned or of low contrast, such as a field filled with flowers, as shown in Fig. F, focus may be difficult to acquire using autofocus.
Responses to these types of situations
(1) Focus on a different subject located at the same distance from the camera, apply focus lock, recompose, and shoot.
(2) Set the camera focus mode selector to M (manual) and focus manually on the subject.
The only way I can think of troubleshooting is to set up some deliberate tests using fixed objects that meet all the criteria above. Build your own and gain confidence that it is, in fact, the lens and not something else.