Autofocus out of focus?

[analog-photo]

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For the last two weeks, on a holiday trip, I have used almost exclusively the "11 point mode" for autofocus. When going through the pictures on the Mac I find a lot more pictures that are totally out of focus (no, not blurred by an unsteady hand....) compared with my one week trip to New York earlier this year. At that time I used almost only "1 point mode". Anyone else experienced this?

 

Since the LCD-screen is useless when outdoors in sunlight, I can not say I always have had a focus confirmation from the camera. I have turned the sound off.

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I find that the one-point focus mode is much more reliable, if by reliable one means: I can capture what I intend to capture. Give the camera 11 focus fields to choose from, and it will do just that: choose for you. This goes for both my X2 and my Vario.

[TMorita]

For the last two weeks, on a holiday trip, I have used almost exclusively the "11 point mode" for autofocus. When going through the pictures on the Mac I find a lot more pictures that are totally out of focus (no, not blurred by an unsteady hand....) compared with my one week trip to New York earlier this year. At that time I used almost only "1 point mode". Anyone else experienced this?

 

Since the LCD-screen is useless when outdoors in sunlight, I can not say I always have had a focus confirmation from the camera. I have turned the sound off.

 

This is the basic problem with contrast-detect autofocus from what I can tell.

I've seen this problem on my other cameras as well.

 

Here's an example of the problem.

Let's say you have a person standing in front a chain-link fence.

If you use multipoint autofocus, the camera will tend to focus on the fence rather than the person.

 

Why?

Because the camera tries to maximize the number of high-contrast edges in the focus region.

The chain-link fence has a lot of wires, and each wire creates two high-contrast edges.

So the camera can get the most high-contrast edges when focusing on the fence rather than the person.

 

So this is why you should use single-point focus whenever possible.

You know what the subject of the scene should be, so you should make sure the camera focuses on it.

The camera doesn't know the subject of your scene - it's just a machine. Don't let it pick the subject.

 

The one thing I would have liked is multiple focus box sizes in single point mode.

Many times I find the X Vario focus box is too large.

The Sony camera shave a small, medium, and large focus box selectable which is nice.

 

Toshi