Talk to me about Metering

Discussion in 'Beyond the Basics' started by chrisburke, Nov 18, 2008.

  1. chrisburke

    chrisburke TPF Noob!

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    so I've heard people say "check your meter" but i've never actually read a thread here on how to meter, and how it helps/what difference it makes... I've read comments like "get a 18% grey card and meter.... can someone elighten me... what does this mean? how do I do it (using the D50.. I've read that the D40's meter sucks) i cant seem to figure it out... and havent had much luck finding info on it..
     
  2. kundalini

    kundalini Been spending a lot of time on here!

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    It's the scale you see in the viewfinder (plus to minus). I have my camera set to read center-weighted. Point to a particular area of the scene and half-press your shutter. By adjusting either aperture, shutter speed or ISO and having the indicator resting at Zero (in the middle) it is metered for a correct exposure. Performing this in several areas will give you an average. Then decide what is best for your shot.
     
  3. Helen B

    Helen B TPF Noob!

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    I guess that the 'check your meter' comment refers to finding out how your meter sets the exposure. You don't need an 18% grey card. Any evenly-lit, evenly-toned surface will do. There are a few ways of doing it. Here's one suggestion. Use aperture priority, and adjust the aperture and lighting so that at your base ISO (100?) you have a shutter speed that is between about 1/8 to 1/30 second. (You can do this exercise for each ISO setting)

    Now take a picture at the shutter speed set by the camera (with the evenly-lit surface filing the frame entirely - use a lens hood and avoid flare-causing light sources), and note the shutter speed. Switch to manual and take a series of exposures by varying the shutter speed, not the aperture. The shutter speed variation is likely to be more precise than the aperture variation, so keep the aperture constant. You can vary the shutter speed in as small a step as you can be bothered with, but I tend to go the first two stops in full stops, then go in third-stops.

    You now have a set of exposures that tell you roughly how your meter is calibrated and how many stops of range you have under and over that. You find this out by looking at the images in the way you normally do - whether you use JPEG or Raw. In JPEG the auto exposure should have an RGB value of about 119 to 121.

    Looking at how your meter/camera behaves in this way may not give you instant answers, but can be a part of an understanding of the behaviour of your camera in terms of exposure.

    Good luck,
    Helen
     
  4. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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  5. JerryPH

    JerryPH No longer a newbie, moving up!

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  6. Garbz

    Garbz No longer a newbie, moving up!

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    In terms of the relation to 18% grey and metering the idea is that all cameras try to return the image to a middle grey tonality. This would instantly become clear to you if you try to photograph a snowy landscape. The picture would be grey not white.

    In your viewfinder you should see the shutter speed, aperture, iso, and meter compensation. In the case of a snowy scene you have the option of either pointing your camera at a grey card to get the correct exposure for the scene, or simply intuitively know that your camera will underexpose the scene by 2 stops.
    In this case your options are flick to manual and adjust the aperture shutter iso combination till your meter compensation reads +2EV, or you can set your EV compensation outright on the camera so it will adjust to +2 in the automatic modes.

    Btw a quick tip. Your average white male (not a surfer, not a computer techie) has a skin tone which appears about 1/3rd of a stop lighter than neutral grey. Perfect for those who love the grey cards yet left them at home.
     

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