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Thread: using f2.8 or brighter lens will FOCUS well ?

  1. #1
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    Default using f2.8 or brighter lens will FOCUS well ?

    will it focus well like in low lighting ? coz i realise that my f3.5 lens at times when in low light condition cant really focus well sometime subject will go OOF

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    Default Re: using f2.8 or brighter lens will FOCUS well ?

    Quote Originally Posted by S11loop
    will it focus well like in low lighting ? coz i realise that my f3.5 lens at times when in low light condition cant really focus well sometime subject will go OOF
    How low is the low lighting u're referring to?

  3. #3
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    Default Re: using f2.8 or brighter lens will FOCUS well ?

    short answer. yes
    depends on your camera's focus sensor sensitivity too
    some better than others

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    Default Re: using f2.8 or brighter lens will FOCUS well ?

    ok thanks ..

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    Senior Member denniskee's Avatar
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    Default Re: using f2.8 or brighter lens will FOCUS well ?

    from my experience @ esplanade outdoor theater

    In low light

    50mm f1.8 + D60 = cant focus

    50mm f1.4 + D60 = can focus

    50mm f1.8 + 1v = can focus
    photography makes one sees things from all angles.

  6. #6
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    Default Re: using f2.8 or brighter lens will FOCUS well ?

    use your Sb800 to help you focus.

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    Default Re: using f2.8 or brighter lens will FOCUS well ?

    AF works by phase matching, in others its like overlapping 2 lines, once the 2 lines overlapped exactly they are in focus.

    thats why patterns can cause AF to hunt or mis-focus even under broad day light.(same pattern means hard to determine which pattern overlap whcih)

    back to the focusing problem, try finding strong lines along the same plane of focus and ths will allow the focus to lock. (e.g the outline of the ear cos it usually stands out quite nicely against the dark back ground for focus.)


    festures of the face under low light has too little contrast for the camera to detect.

    AF works under a certain range of EV( light values). eg EV1 -21. means brighter lens will work better cos allows more light in and thus easier to get at least EV1

    more importantly to work around the problem be focusing on strong lines then getting brighter and brighter lenses. 2.8 is already pretty good for most situation even outdoors at night.
    just my 1 ct worth

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