Autofocus problems at close-range

Discussion in 'Photography Beginners' Forum' started by Player_1, Jan 22, 2007.

  1. Player_1

    Player_1 TPF Noob!

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    I've been doing some close-range photography with my Fujifilm A500. The Fujifilm A500 seems incapable of focusing on a graphic at the far right or far left.

    I have some old documents, especially from the 1900s and such. If the page is full of text, the camera seems to get all parts of the page. However, if part of the page has a tiny bit of text, the camera can't correctly focus. I don't understand why it can't focus.

    Why can the camera only focus when there are many words and such on the page instead of a tadbit of information?

    For instance, I photocopy a document filled with text. This will easily by focused on.

    I photocopy a document with a tiny bit of text, perhaps three sentences, and it can't be focused on.

    I tried turning off auto-focus, but that didn't work. It seems the camera/image still couldn't retain the sharpness. The image blurs out.

    I don't understand why the camera can retain sharpness on the documents filled with text, and I don't understand why it can't retain sharpness when there is a small amount of text. It seems the fonts are the same. It doesn't make sense to me.

    Is there a way to retain sharpness for documents with a small amount of text?

    I did something I didn't want to do to fix this problem. I took a sheet of notepad, placed it on the "white space," and I photographed the document. The camera must have focused well because there were more graphics to take a picture of and focus on, but I'll have to edit out the piece of notepad paper.

    I don't like having that piece of notepad there.

    Are there certain ways point-and-shoot cameras focus on materials? I often notice the sharpness decreasing as things go away from the center of the image. I don't understand how to get sharpness all around. Maybe it's the camera's lens, or maybe it's something else.
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    When a camera is focusing...it's picking one or several point in the frame to use a focus targets. There needs to be some contrast in those areas...or else the camera's AF system can't see anything. With your camera...it may be that there is only an AF sensor for the centre part of the frame...which would explain why it won't focus unless there is text across the centre (or the whole page).

    The solution is to focus and recompose...aim the centre of the viewfinder at the part of the page where there is text, let the camera focus...then lock the focus (usually just hold down the button half-way)...then recompose and snap the image.

    Or if, you camera an subject are stationary...just focus once and then there is no need to focus again with a new page.
     
  3. Player_1

    Player_1 TPF Noob!

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    How can I tell what AF system and AF sensor a camera uses?
     
  4. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Check the specs.

    It may or may not be in the manual...and/or on a site like DPreview.com
     

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