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Old Oct 27, 2008, 7:33 AM   #1
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Hi everyone, just bought the A300 and was wondering if the auto focus is supposed to work all the time. Whenever i move the camera the lens seem to adjust,is this common on this model? thanks for any replies.... Raoul
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Old Oct 27, 2008, 9:08 AM   #2
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From page 74 of the A300/A350 Instruction Manual:

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AF-S (Single Shot AF) - The camera focuses on and the focus is locked when you press the shutter button halfway down.

AF-A (Automatic AF) - When you press and hold the shutter button, the focus is locked and if the subject is in motion, the camera continues to focus.

AF-C (Continuous AF) - The camera continues to focus while the shutter button is depressed and held halfway down.

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It seems your A300 is set to AF-C, which is useful when the subject is moving constantly, but the camera has a lot of work to do and will drain the battery faster. You can change that setting in the camera's menues.
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Old Oct 27, 2008, 9:56 PM   #3
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Thanks TCav, yes it was set to that should i put it on AF-S ?
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Old Oct 28, 2008, 7:08 AM   #4
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If all your shots are posed, or if the subject never mooves, then AF-S is a good idea.

If there might be some action in your shots (kids, animals, etc.), AF-A might be a better idea.

I use AF-C, but most of my shots are action (equestrian, candid portraits, etc.) and I always have extra batteries handy.

AF-A is the default setting, btw.
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Old Oct 28, 2008, 2:10 PM   #5
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mine even focuses with the lens cap on! i have the same issue and it does not matter which setting. since most of my pics are wildlife, it is a problem when the noise of the focusing scares the critters.

i think i will contact sony about it. maybe they can issue firmware to correct it.

ellen fl
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Old Oct 28, 2008, 4:34 PM   #6
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If your camera is focusing without a half press of the shutter button, you probably have Eye Start Autofocus enabled (so it's starting to focus whenever anything is in close proximity to the sensors under the viewfinder).

Simply go into your Setup menus and set Eye Start Autofocus to off. ;-)

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Old Oct 29, 2008, 6:45 AM   #7
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Thanks JimC, you are 100% right that solved the problem. Great to have a forum that has so many clever people in it .
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Old Oct 29, 2008, 7:42 AM   #8
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I think the Eye Start AF feature is good for some conditions.

But, unfortunately, anything in close proximity to the sensors under the Viewfinder can trigger it on some of the new Sony models like your A300.

The Sony A700 model intended for sale in the U.S. has grip sensors to help out. The camera must see something in close proximity to the viewfinder *and* information from the Grip Sensors before Eye Start AF is activated.

But, because of European regulations on nickel content, Sony ended up manufacturing two different A700 bodies (one with grip sensors, one without grip sensors).

Rather than continue that trend (different bodies for different market areas), Sony eliminated the grip sensors from newer models like your A300. Hence, the problem you can have with AF starting when you may not want it to.

The A900 doesn't get eye start AF at all, so it looks like Sony decided this feature is not worth the aggravation. Of course, they may redesign the grip sensor at some point to meet European regulations and reintroduce this feature on new camera models later (only time will tell).


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Old Oct 29, 2008, 12:59 PM   #9
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thanks, jim. i will check mine when i get home tonight. the constant sound of focusing kinda drives me nuts! i suppose having the camera dangling at my side is close enough to my body/arm to trigger it?

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Old Oct 29, 2008, 1:26 PM   #10
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Exactly. Anything that is close enough (and I don't know what the exact distance is) will trigger the Eye Start Autofocus feature if it's enabled in your setup menus.

If you disable Eye Start Autofocus, the sensors under the viewfinder still work for turning off the LCD (so that it doesn't stay on and blind you when you want to use the viewfinder without turning the display off first). But, with Eye Start disabled, you don't have to worry about the camera focusing without a half press of the shutter button.


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