metering....again....grey card

Discussion in 'Photography Beginners' Forum' started by puyjapin, Mar 21, 2009.

  1. puyjapin

    puyjapin TPF Noob!

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    Ok i will admit I still dont fully get metering. I tend to take a few shots till one looks correct, which I would rather not do. Id prefer to get it right the first time!
    Am i correct in thinking this is how the grey card works.....if im in a situation in manual mode which i use most the time now and i put a grey card in front of the camera with the light refelcting off it I simply adjust my shutter/aperture until a correct exposure is shown(correct as in in the middle of the meter) does this then mean that when i poin the camera at anything with the same light falling on it the exposure will be correct even tho the meter miht now bw showing under or overexposed?
    thanks
     
  2. Josh66

    Josh66 Been spending a lot of time on here!

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    Yup, that's basically how they work.
     
  3. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    Huh??
    I thought grey cards were only for setting your white balance for a shot and had little to no use for actual metering for taking a shot since one could have major highlights or areas of shadow in a shot which would then be exposed incorrectly (if they were the intended main subject of a shot).

    Firstly if your still not getting metering I think you need to find yourself a local camera club or see if there are any local members who are willing to give you some in person help with metering. I think I am right in thinking that you might not learn best from books and learn better when out working with the gear.
    Also never get the impression that the "pros" always get their exposure right first time - many will use bracketing if they can to get the "right" settings for a shot.
     
  4. EhJsNe

    EhJsNe TPF Noob!

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    I got a little confused....if the you point the camera at the grey card and get the meter to say you have a correct exposure, anything with the same light falling on it WILL be correctly exposed, no matter what the meter says.

    The reason is because the camera ises grey as a reference, it will give you different reaqding if you point it at a black wall than what youd get if you pointed it at a white wall. even if there right next to each other.

    The camera will tell you to use a faster shutter speed on the white wall (to underexpose it and make it grey) and a shorter one on the black wall (to overexpose it to grey) This method works very well 80% of the time. The only time it doesnt work to well is when you are photographing something black or white.
     
  5. Josh66

    Josh66 Been spending a lot of time on here!

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    I use my grey card for both (metering and WB), though not as often for metering (I usually just spot meter off of something).
     
  6. KvnO

    KvnO TPF Noob!

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    I was taught to use a gray card to meter tricky situations as the camera will always expose it properly (as previously stated). No one ever mentioned getting your white-balance correct with one. But, now I know.
     
  7. Josh66

    Josh66 Been spending a lot of time on here!

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    For white balance you don't really need a "white" card - you need a neutral (grey) card. White would work too, but it could get blown out much more easily than a grey card. If your white balance reference did get blown out, it would be pretty much be useless - R, G, & B values would all be maxed out.
     
  8. Dao

    Dao No longer a newbie, moving up!

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    Quote from Wikipedia

    "By placing a gray card in the scene to be photographed, oriented at a defined angle relative to the direction of the incident light, and taking a reading from it with a reflected light meter, the photographer can be assured of consistent exposures across their photographs. This technique is similar to using an incident meter, as it depends on the illuminance but not the reflectivity of the subject.

    In addition to providing a means for measuring exposure, a gray card provides a convenient reference for white balance, or color balance, allowing the camera to compensate for the illuminant color in a scene."




    http://en.wikipedia.org/wiki/Gray_card
     
  9. puyjapin

    puyjapin TPF Noob!

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    so the card is no good if u meter off it then look at a subject 100 yards away in a landscape?? Also will the meter pick up stuff any distance from the camera? I tend to use matrix metering.
     
  10. Christie Photo

    Christie Photo No longer a newbie, moving up!

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    Yup. And not just the camera (exposure)... but everything else we measure in photograpy. 18% gray is our benchmark. It's our standard against which everything can be measured or assessed.

    Think of it this way: How can we say if the room temperature is too warm or too cool if we don't say what we want to achieve. If the goal is to make it comfortable for humans, then 40° F is too cool. However, if the goal is to store ice, then 40° F is too warm.

    So it's important to remember when deciding what is too much light or too little light for proper exposure, the meter is telling us how to achieve 18% gray. If you measure the light reflecting off a white subject (something that reflects 90% of the light), and the meter is telling us how to achieve gray, then we have unexposure if the goal is to make the white subject appear white.

    We have to assess the scene and make some decisions. What if something in view is transmitting light? What if we want to preserve shadow detail in a dark subject? Maybe personal preference comes into play. After all, some folks like the room to be a bit warmer or cooler than others.

    – Pete
     
  11. Torus34

    Torus34 No longer a newbie, moving up!

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