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Old Aug 25, 2008, 12:50 PM   #1
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How exactly to you focus to infinity with the A300. Will any lens do it? is it a setting you select somewhere on the camera?

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Old Aug 25, 2008, 9:14 PM   #2
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Most any lens will focus to infinity, unless you're doing something that keeps it from doing so. For instance, a lens with extention tubes or close up lenses wil not focus to infinity.

Switch to manual focus, turn the focusing ring all the way in one direction. Ifstuff that's really far away is out of focus, turn the focusing ring all the way in the other direction.
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Old Aug 26, 2008, 12:17 PM   #3
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So yesterday I received my Tamron 70-300, I switch to manual focus and turn it to the little infinity symbol (sideways 8) but it wont turn all the way there. There are the standard numbers (ft/m) then there is a little "L" shaped symbol and then after that is the infinity symbol. it stops at the "L" shaped symbol everytime and wont' let me turn it more to the infinity symbol.

Am I doing something wrong? Is the lens bad?

Also, to clarify more about focusing to infinity, Will everything far away be in focus but close things be out of focus? or will everything near and far be in focus?

Thanks
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Old Aug 26, 2008, 6:58 PM   #4
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firstascent wrote:
Quote:
So yesterday I received my Tamron 70-300, I switch to manual focus and turn it to the little infinity symbol (sideways 8) but it wont turn all the way there. There are the standard numbers (ft/m) then there is a little "L" shaped symbol and then after that is the infinity symbol. it stops at the "L" shaped symbol everytime and wont' let me turn it more to the infinity symbol.

Am I doing something wrong? Is the lens bad?
The little sideways 'L' is the index mark for theinfinity symbol. The numbers are narrow enough to not need one, but the infinity symbol is wider and would be too close to the last number, so they move it over and put the little index mark for infinity. That's as far as it's supposed to go.

firstascent wrote:
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Also, to clarify more about focusing to infinity, Will everything far away be in focus but close things be out of focus? or will everything near and far be in focus?
Everything within the depth of field will be in focus.

According to DOFMaster.com, when focused at infinity (for purposes of this calculation, 10,000 feet) at a focal length of 300mm and f/5.6, nothing will be in focus that is less that 2,070 ft away. At a focal length of 70mm and f/4.5, however, things as close as 176 ft will be in focus, but nothing closer.
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