D5000 slow/failed autofocus

[cosine4]

Just got back from a trip taking quite a few pictures and encountered for the first time very slow and even failed auto-focus attempts. Sometimes I could just release and repress the shutter release 1/2 way and it would find the subject. Other times if I changed the zoom it would be able to find the subject. Others I had to go to manual focus mode. This was very frustrating because I missed some opportunities. Also this is was large subjects (Empire State Building, Washington Monument, as well as other not so large items) and well within he focal range of my lenses. I had this happen with all three of my lenses on different occasions (Nikkor 18-55, 55-200, and 35/1.8). Is this something that can be affected by humidity (I was shooting on very humid days)?

The only thing that I did change was I turned of the AF Illuminator as I was taking some shots of a theater show and didn't want to be a distraction to the performers or other audience members. I tried switching this back on but didn't notice any improvement.

Should I consider contacting a service center for warranty?

Thanks for any advice!

[candleman]

So... you were shooting at daytime?.... or at night?
i can understand slow.difficult focus in the dark.. but on a bright day there shouldnt be any problem.


not sure what could be up....

[cosine4]

Originally Posted by candleman

So... you were shooting at daytime?.... or at night?
i can understand slow.difficult focus in the dark.. but on a bright day there shouldnt be any problem.


not sure what could be up....

This was happening outside on sunny days.

[dcclark]

Were the subjects big and flat (no details)? For example, if you were taking a photo of a large monument which was relatively smooth, there would be no edges or details or texture for the AF system to catch on to. It's like trying to focus on a clear blue sky: there's nothing to be IN focus!

That may have confused the system. Also, have you been using one of the modes that chooses the AF point for you? If so, it may have mistakenly chosen a point with no details in it, as opposed to one with the real subject -- or none of the AF points may have had enough detail to focus on (i.e. the edges of the building, or textures, fell outside all of the AF points).

To solve that last problem, I usually stay in the mode where I can choose my focus point manually.

[Nikonbby]

Originally Posted by dcclark

Were the subjects big and flat (no details)? For example, if you were taking a photo of a large monument which was relatively smooth, there would be no edges or details or texture for the AF system to catch on to. It's like trying to focus on a clear blue sky: there's nothing to be IN focus!

That may have confused the system. Also, have you been using one of the modes that chooses the AF point for you? If so, it may have mistakenly chosen a point with no details in it, as opposed to one with the real subject -- or none of the AF points may have had enough detail to focus on (i.e. the edges of the building, or textures, fell outside all of the AF points).

To solve that last problem, I usually stay in the mode where I can choose my focus point manually.

These are all true points. I shoot with a D3000, baby brother to your camera, and I've found the same problem with my camera, but only in really dark situations. I can't even get it to focus properly in Auto mode in the dark (I was just experimenting with it. Didn't really expect it to work).

I know that sometimes, the camera just doesn't auto-focus like I want it to. I know that full manual focus overrides a lot of the annoying lag and stop that the auto-focus sometimes takes in difficult situations, but I was always wary because I tried manually focusing for a while and found that things were tack-sharp like they ought to be. I recently discovered, however that there is a small green light that comes on in the left corner of your viewfinder when you have a proper focus. Another trick is to let your auto-focus go through the back and forth focusing (when it's attempting and failing to find the correct focus) a few times and when it seems to be pretty well in focus, switch it to manual. This seemed to get it pretty well in focus for me one night when I was out taking pictures after dark.

Though, it does sound like yours was having definite issues. I'd check some of the things that dcclark mentioned, and then I'd see what happened. It may need some repairs. The tips I gave generally work if something is too difficult for it focus on. And that little light makes manual focus just a little bit less scary.

Hope this helps!

[nokiN]

In your camera manual it describes certain situations that are hard for AF to handle, like:

• regular repeating geometrical patterns (like the windows on a tall building)
• little or no contrast between subject and background
• the focus point has areas of sharply contrasting brightness
• background objects appear larger than your subject
• the subject contains many fine details

which is what they list in the D300 users manual.