50mm 1.8 question

Discussion in 'Photography Beginners' Forum' started by Lead_Cenobite, Dec 25, 2007.

  1. Lead_Cenobite

    Lead_Cenobite TPF Noob!

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    Hi, I just got the canon 50mm f/1.8 lens and noticed that when I have it on autof focus, it only focuses in on a very small area as opposed to normally when the two end focus spots will be flashing and the whole image is in focus. Is there a reason for this that I am overlooking because I was planning on using this at a concert on saturday but I don't want to take a picture and have the headstock of a guitar in focus and the rest of the picture be useless. Any help is appreciated.
     
  2. Josh66

    Josh66 Been spending a lot of time on here!

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    Sorry if I'm misunderstanding this....

    It sounds like you want more DoF (Depth of Field). Use a smaller aperture (bigger f/#) and it will bring more of the image into focus. It won't make any difference if it's on auto or manual focus.

    This will make your exposure times a little longer though, so for a concert you might have to shoot wide open (or up the ISO, or both).

    OR... Are you talking about the focus points flashing (in the viewfinder)? You can select which one you want to use, maybe you accidentally changed it?

    The whole image will only be in focus if you have sufficient DoF, how much DoF you need will depend on where everything you want included in the image is.
     
  3. monkeykoder

    monkeykoder TPF Noob!

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    Another point is that unless you're taking a picture the aperture is at maximum (unless you use your depth of field preview button).
     
  4. Alex_B

    Alex_B No longer a newbie, moving up!

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    sounds like you want more depth of field. to achieve that you need to stop down the lens to f/4 or even f/8.

    If you shoot at concerts though, that will be possibliy very little available light? if so, you will want the aperture wide open at f/1.8 to get as much light as you can without having to use really slow shutter speeds.

    You see, it is always a compromise.

    I'd reccommend to use only one AF point, focus on what you want to be in focus, recompose and then shoot. The best way to go with the aperture wide open IMHO.
     
  5. Sideburns

    Sideburns TPF Noob!

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    You definitely do want more depth of field. But what you're talking about has nothing to do with focus points.

    The different focus points will only light up at the same time, if the objects are the same distance from you (or at the same focusing distance).

    Focus on a wall far away, and most of the points should light up.

    I only use one focus point.
    A camera technically only focuses on one thing at a time, but for some reason we have 4 gagillion AF points...

    Also another thing...
    If you're not that close to the stage, you can use f/1.8 anyways and you'll get the whole guy in focus.
     

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