Light meter

Discussion in 'Photography Beginners' Forum' started by Hill202, Sep 17, 2007.

  1. Hill202

    Hill202 TPF Noob!

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    I've just started reading "Understanding Exposure". The authur talks about using the camera's light meter to find the correct shutter speed. He talks about taking a reading and recomposeing.

    The books seems to be very informative but I don't understand the metering. What is metering?

    Perhaps the book will offer more info later on this, as I said I have just started the book.

    He also discusses that his camera indicates what the correct shutter speed should be, does a D40 do that?

    Thanks
     
  2. Big Mike

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

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    Just about every 'modern' camera has a light meter. That's how it knows what settings to use.

    To activate the meter, just half press the shutter release button. The camera should show you two numbers in the viewfinder or on the screen. One is the aperture value (F number) and the other is the shutter speed. These two numbers (plus the ISO setting)...are your meter reading.

    So for example, you could 'take a reading' and your exposure value would be something like 1/60, F4, ISO 200. You could change any one of those (without changing the others) and it would change your exposure. Or, if you changed them relative to one another, the exposure might stay the same. For example, 1/30, F5.6, ISO 200 is the same exposure.

    Now that you know that. You need to know how the meter comes up with those numbers. It's set to always give you settings for 18% grey...or a mid tone exposure. So if your scene is mid toned...then the settings the camera gives you, will be accurate. If, however, the scene is darker, the camera will still think it's a mid toned scene...but just with less light...so it will try to lighten up the scene...which will make your shots, too bright. Same thing with a bright scene, the camera will try to darken it. This is where you need to know what the meter is seeing and you have to override it...either by using manual mode or EC (exposure compensation). You will want to look at the 'meter/ruler' on the camera and adjust the needle to be positive for brighter scenes and negative for darker scenes. I'm sure it's all in the book...or it should be.
     
  3. Garbz

    Garbz No longer a newbie, moving up!

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    Yes. Metering is just that. It's metering the light. The camera has a light metre built in which calculates the required exposure value and then picks the required shutter speed, aperture, and iso to match that exposure value.

    The manual http://www.nikonusa.com/pdf/manuals/noprint/D40_noprint.pdf on page 5 shows how the camera gives feedback, and it is described on page 43 and 47. In Automatic, P, A, or S modes the metered settings are simply shown as the current shutter speed aperture iso combination. In Manual mode you set all the variables and the little bar display on the bottom show if you are above or below the metered value.

    /EDIT:Bah mike beat me.
     
  4. Hill202

    Hill202 TPF Noob!

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    Ahh.. when all else fails I should read the directions :lol:
     

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