Autofocus issue with Sigma 10-20mm? Help!

Started Jan 15, 2014 | Discussions thread
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Leonard Shepherd
Leonard Shepherd Forum Pro • Posts: 10,545
Re: I have come to a different initial conclusion

banflu wrote:

recently I was on holiday so I used the camera (and this Sigma lens) quite a lot .. and I've had quite a number of out-of-focus photos. I later realised that they are never out-of-focus if I use live view. Of course, live view is much slower so it is quite an issue.

If you bought a similar Nikon lens instead the Nikon lens instructions would caution ordinary AF is not always accurate with the fine detail or small subjects under the AF rectangle. This can be common with wide angle lenses.

As you have not posted any images it is likely you have problems with subjects that are poor for ordinary AF, and the photos that are sharp are better AF targets. Small example images could help clarify if this is your problem.

Nikon suggest when AF is not good find an alternative subject at the same distance (not always possible) or use manual focus.

LiveView as you noter is much slower to use but as it detects a very small segment of the subject it can sometimes beat ordinary AF with static subjects.

LiveView is not much use with moving subjects, and also needs detail in a horizontal direction to ensure it works accurate.

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Great images are often of good subjects.
If they are great images does what lens, body or technique was used matter more than the skill of the photographer?

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