metering...i still dont fully get it

Discussion in 'Photography Beginners' Forum' started by puyjapin, Jan 28, 2009.

  1. puyjapin

    puyjapin TPF Noob!

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    OK, ive ordered understanding exposure for some bed time reading...
    Is metering something used in full manual mode or only aperture and shutter mode. I am of the assumption that when in aperture priority the shutter speed varies according to the amount of light coming in, thus if i wanted to expose something differently i would point the camera at a lighter or darker area, then lock that exposure...which is metering ??
    when i use full manual mode as the shutter and aperture are both set and fixed what would the effect of pointing the camera at a lighter or darker area do as there is no exposure to lock as it is fixed. Can someone explain as I think i still have this all arse about face... thanks
    :er:
     
  2. tirediron

    tirediron Watch the Birdy! Staff Member Supporting Member

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    Metering is used in all modes. In manual, you will set each value (ISO, Shutter speed, and Aperture) yourself. In Aperture Priority, you set the desired aperture, and the camera will vary the shutter speed to suit. In Shutter priority, you set the desired shutter speed and the camera will set the appropriate shutter speed. In 'Green Box' mode (Nikon) the camera will set all values based on pre-programmed algorythms.

    If your camera is in manual mode and you meter off of a subject with a particular light value, and then point it at a significantly darker subject, the image will be much too light. If you point it at a much lighter subject, the resulting image will be over-dark.
     
  3. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    when you meter in aperture or shutter priority mode the camera will adjust your shutter or aperture to give you a correct exposure based on the one setting you control (aperture or shutter) and also the ISO you have set.
    there should be a meter bar on the camera display with an arrow on it - normally the arrow is in the middle which is an "ideal" exposure, however if you use exposure compensation you can force the camera to under or overexpose the shot (move the arrow either side of the middle).
    for example you might be shooting action and want a slightly faster shutter speed than aperture priority mode is giving you - so you can choose to underexpose the image, thus tell the camera to select faster shutter speeds.

    In full manual mode the meter bar operates differently, instead of being a fixed position that the camera aims to reach, the meter bar will show you how the settings you have selected (aperture shutter speed and ISO) will meter - either under, over or perfect exposure. This requires you to know the order of importance for those settings for the shot you are taking - action might demand that you shutter speed is your primary setting, or landscaping aperture would be your primary - so you would set your primary and then adjust the other settings to achive a correct exposure.

    Note that a correct exposure is one which exposes the shot as you want it to be, however there are conventions for exosure which the camera will try to keep to (that of a middle ground exposure).

    The exposure reading is affected by what metering mode you pick - which tells the camera how much of the frame to detect light from and then meter for - I will stop here as metering modes is something that I really don't know well
     
  4. puyjapin

    puyjapin TPF Noob!

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    does anyone know where the metering bar is on a d40 then? also if you can use exposure compensation whats the point in metering?
     
  5. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    exposure compensation only changes the point on the exposure bar that the camera meters to when you are shooting in a semi auto mode (like aperture or shutter priority) of a full auto mode. When you are shooting in full manual you are setting all 3 settings and thus the meter is just reporting what your settings will give you in the form of an exposure - you can choose to under or overexpose as much as you wish.

    As for where the bar is there should be a note inyour camera manual detailing the menu and display setups (if you have lost your manual then you can get one off the nikon main website
     
  6. puyjapin

    puyjapin TPF Noob!

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    thanks for your help, although i still dont really fully understand metering. Do you guys meter most of the time, in terms of pointing the camera at a different light source before re composing the shot and pressing the button...or s it something that does not need to be used all the time?
     
  7. ann

    ann No longer a newbie, moving up!

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    you still need to make a decision as to what is the most important item i.e. DOF or shutter speed, then the meter matches the amount of light reflecting off the subject and suggests the other value. If you want to over ride that decision you can then use your exposure compensation dial. Do you want to overexpose or underexpose, and then by how much?
    if you make a change without using the exposure comensation dial, the camera will automatically adjust either the shutter speed or the fstop and you will get the same amount of light but in a different manner.

    With manual mode, you still need to start with some value, either fstop or shutter, however, you can then move the oposite value without changing the other., this is done by dialing the change and watching the "clicks" at the bottom of the viewfinder screen.
    +2 ...+1...0...-1...-2 an example. so you will start will the click at 0, which means the meter thinks this is the proper exposure and then you can move the bar either one way or the other to make adjustments.
     
  8. ann

    ann No longer a newbie, moving up!

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    you meter all the time.

    learning to meter is a skill that takes time and work.
    you have to be careful where your pointing the lens as the meter can get confused.

    for example, metering off someones face then backing up allowing the meter to be influrence by a lot of bright lights. then the face is going to run the risk of being underexposed.

    this just takes practice. You have done the right thing in getting Brian's book as it should clear things up for you as there are lots of examples.

    the other way would be to find a mentor or take a class that will review and go into more detail face to face which can be very helpful
     
  9. cosmoepic

    cosmoepic TPF Noob!

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    look through your view finder you'll see a bar at the bottom
     
  10. Big Mike

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

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    The book 'Understanding Exposure' can be a bit confusing because (from what I gather) it teaches metering by pointing the camera at different things, locking the exposure, recomposing and then taking the shot. Basically metering off of different things.
    There is nothing wrong with that, but it doesn't necessarily tell you what is going on.

    You can 'meter' anything...even the shot you are trying to take, without having to point the camera at something else.

    They key is understanding what the camera is seeing and what it's trying to do with that. Knowing how to read you meter means knowing when to change the exposure away from the --0-- on the meter. You can do this in manual mode or with exposure compensation in any other mode. The point is that you don't always want the 'needle' on the --0--.

    In the digital era, some people have replaced 'metering' with chimping. Basically, you take a test shot, check your exposure with the histogram, adjust your exposure and shoot again.

    Read these two articles...
    Understanding Histograms
    Expose Right
     
  11. potownrob

    potownrob TPF Noob!

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    the bar is in the middle of the lcd screen when you're in shooting mode (shutter pressed down recently) and it's at the bottom of the viewfinder in the middle. In both cases, it is next to the ISO indicator. I usually keep my exposure compensation set to -.7 so the bar is almost always off center with marks to the right of the center of the bar. as for the point of metering, without a light meter you'd have to guess the correct exposure for a shot. After a while, you may get good at guessing the correct exposure settings for a given situation, but the meter helps you to expose for what you're shooting, metering the whole frame in matrix mode, the whole frame with priority on what's in the middle of the frame in center weighted mode, and metering for what's at the very center of the frame in spot metering mode. Then, from what the meter determined to be correct exposure, you can make minor adjustments to get the exact exposure you are going for.
     
    Last edited: Jan 28, 2009
  12. puyjapin

    puyjapin TPF Noob!

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    thanks guys, im joining a local photo club soon so hopefully i will get to learn. As you said face to face is a much easier way to learn.you gys have been very helpful on here. Im pretty new to photography and dont have any friends who own SLR's so im on my own at present. Just to confirm if you point the camera away from the subject and then return to the subject does the meter reading change back if its not locked or will it remain for a few seconds while the shot is taken. Im looking forward to getting the book!!!!!!!!!
     

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