'Depth' of depth of field

Discussion in 'Photography Equipment & Products' started by colintinto, Sep 14, 2005.

  1. colintinto

    colintinto TPF Noob!

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    Hi All,

    Bit of a techy one... I'm still toying with the idea of getting a 50mm f1.4 for my 300D (Bid for a few on eBay but 2nd had are so close to the price of new - what's the point!).

    However - does anyone know how to work out the 'depth' of the area in focus for such a lens? I've noticed with my other lenses, even at only f4.0, that taking a close up portrait of a face at 45 degrees can often end up with one eye in focus and the other out.

    I seem to remember, a while back when I was learning about DOF, that the area of focus is related to the magnification of the lens, and that it's different for say a 50mm at f4 and a 120mm at f4.0, but I don't know which way round it works.

    I'm worried that I buy the f1.4 and find I can only use it from f4.0, and would have been better to stick with what I've got...

    Colin
     
  2. ferny

    ferny TPF Noob!

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  3. colintinto

    colintinto TPF Noob!

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    Excellent, thanks ferny. Very useful little tool that.

    Colin
     

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