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Old Jul 25, 2002, 4:36 PM   #1
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Default Bad Autofocus On Most Digicams

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Hi, I've had an Olympus C-2000Z and a Sony DSC-F707. Both of these cameras have absolutely, positively horrible autofocus regardless of other settings. I have seen messages on this site that indicate that this problem is not isolated to just these brands.

The resolutions were 2 and 5 megapixel, respectively, and I've seen plenty of sharp photos (when focussed at infinity). And no, I'm not mistaking digital zoom for a useful feature.

So first of all, does anyone have a digital camera that actually does a good autofocus? My definition of bad and good autofocus is as follows:

I believe that the root of the autofocus problem lies in bad engineering, and has nothing (usually) to do with other camera settings. What happens in a bad autofocus is that the objects closest to the camera (or at the bottom of the frame, which is usually the same thing due to perspective) become sharply focussed, while the rest of the image is allowed to blur beyond belief. Perhaps this is due to the fact that in a bad autofocus, the camera does not go through all possible focus settings (for the given zoom level), and instead just stops as soon as anything at all is in focus, which for mechanical reasons happens to be the closest objects. Take a photo of your living room as an example. The arm of the chair closest to you will be in razor-sharp focus, while the vast majority of the image, including what's in the center, will be blurry. It is amazing to me that the engineers of these systems would not realize that what is in the center of an image and/or what takes up the most area is what is most important to focus on.

So good autofocus, then, would be an algorithm that at the very least focussed on the center of the image (duh!) or executed some compromise between total area in focus and center weighting.

I have bent over backwards to convey this to Sony (as one of many examples). Sony simply does not care or understand. Their $1000 5-megapixel paperweight is only good for manual focus at infinity.

Returning to the original point, it would be great to know of a camera company that has a good autofocus algorithm.

STEVE: On this off chance that you, the webmaster, see this post, it would be great to add an autofocus test (like a furnished room) to your very detailed and useful reviews.
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Old Jul 25, 2002, 4:41 PM   #2
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I have a Coolpix 4500 and I can sit on my sofa, take a picture with the coffee table, my feet on the table, the TV on in the back ground and have all aspects come out clear in the picture, even the reflection of the stuff on my table in the black areas on the TV in AF mode.
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Old Jul 25, 2002, 10:12 PM   #3
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Could you post a sample of the condition you are describing? There are two separate issues here. First, there is the actual point of focus which is generally selected by the camera by means of detecting maximum contrast. Then there is the issue of depth of field where only a limited space from front to back can be in focus at the same time.

Actually, I have both the cameras which you mention (C2000Z and DSC-F707) and I've not experienced the problem you describe with either. The Olympus has always taken crystal clear in-focus images and the F707 appears to have one of the better autofocus functions among the prosumer/consumer cameras.

Here are a couple images - one from each which I find are typical of my cameras. I'm comparing these with a large number of digicams (I have 20) so I'm a little perplexed as to the reasons why yours are not functioning correctly. It's always possible that you have two malfunctioning cameras - statistically improbable, but possible.

Best regards,


[Edited on 8-22-2002 by Lin Evans]
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Old Jul 27, 2002, 1:29 AM   #4
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That's great to know, for me and everyone else here. My next camera will probably be a Nikon Coolpix.

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