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    Exposure Compensation: finally a jargon free method for getting perfect exposure

    | Photography Tips | 27/06/2013 00:01am
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    Are you tired of pictures looking too dark or too bright. Poor exposure is one of the most common problems photographers face, but you don’t have to take it anymore! This jargon-free guide to using exposure compensation explains everything from how much exposure compensation you should use on down to when your camera can get it wrong.

    Exposure Compensation: finally a jargon-free method for getting perfect exposure

    Image by Bob Winsett / Getty Images

    Common questions about using exposure compensation

    What is exposure compensation?
    Exposure compensation is a way of overriding your camera’s exposure meter and making your photos brighter or darker. You may do this for artistic effect, or to correct an error made by the camera’s automatic exposure system.

    Sophisticated box of electronics it may be, but your DSLR can still be fooled by scenes or subjects that are very bright or very dark, and this can result in pictures that are too dark (underexposed) or too light (overexposed).

    I paid a lot of money for my camera, so why can’t it expose a photo correctly?
    Camera meters are tuned to provide an average exposure. Point your lens at a lush green landscape – which is typically average in tone – and there’ll be no problem. Fire away!

    However, if that same landscape is covered in snow then it will reflect more light back towards the camera. The metering system interprets this as an average mid-tone scene that’s too bright, and it reduces the exposure accordingly.

    The result? A grey, underexposed picture when it should be white and bright.

    The reverse is true when you’re photographing a dark subject – the camera sees this as a mid-tone subject that’s too dark, and will try and brighten it up, leading to a grey, overexposed picture.

    Using exposure compensation enables you to correct these metering errors, so that you can make bright scenes bright again, and restore overexposed dark scenes to their original dark state.

    How do I know when I need to use exposure compensation?
    Once you’ve taken a picture, play back the image and check the histogram alongside it on the rear screen – you might have to press a button marked Info or Display or similar to make the histogram visible.

    This graph represents the levels of brightness in the image, from pure black (on the left) to pure white (on the right). If the histogram is bunched up to the right end of the graph, it’s likely that your picture is overexposed.

    If it’s bunched to the left then it may be underexposed. If you want to correct this, you’ll need to dial in exposure compensation and take another shot.

    What is exposure compensation?

    So how do I do it?
    There are a number of ways you can make exposure adjustments, but the easiest is to hold down the button marked ‘+/-’ on your camera, then rotate the camera’s control dial.

    On the majority of Canon SLRs, there isn’t even any need to press a button – simply spin the large wheel on the back of the camera. Look through the viewfinder or check your camera’s top LCD screen as you do so.

    When you turn the dial in one direction, the indicator on the exposure scale will move towards the ‘+’ end, which will make the next shot you take brighter.

    Turn the dial in the other direction and the indicator will move towards ‘-’, making the subsequent shot darker.

    How much do I need to use?
    The brighter or darker your subject, the greater the amount of exposure compensation you’ll need to apply. Depending on the lighting conditions, you might need to add two or more stops of positive compensation when shooting a white flower, but only two-thirds of a stop when shooting someone with pale skin.

    What do you mean by ‘stop’?
    Most DSLRs offer a compensation range of -5EV (Exposure Value) to +5EV. Each of the steps (or stops) along this range gives an exposure that’s twice as bright or twice as dark as the one before it.

    A setting of +1EV gives one stop more exposure, letting in twice as much light, while a setting of +2EV gives two stops more exposure and quadruples the amount of light.

    Going in the other direction, a setting of -1EV gives one stop less exposure, with half as much light reaching the sensor.

    For more precise exposure compensation, digital SLRs will enable you to fine-tune the exposure in third or half stops – you’ll need to choose one or the other in the camera’s menu.

    This is particularly useful when you’re using your camera’s pattern or multi-segment metering mode, as you may only need to make subtle adjustments.

    Why would I need to make small adjustments in exposure?
    ‘Intelligent’ pattern metering modes, such as Canon’s Evaluative and Nikon’s Matrix, take their exposure readings from across the whole frame and then essentially apply their own exposure compensation.

    As well as taking into account the difference in brightness between different parts of the picture, their metering algorithms also factor in focusing distance and (in some instances) colour, before calculating a suitable exposure.

    If you dial in large amounts of compensation on top of this, you may end up with grossly over- or underexposed pictures. So, it’s best to start with small adjustments, then check the histogram and reshoot as necessary.

    I’ve heard that I don’t have to worry about exposure when I’m shooting in raw. Is that true?
    Although you can tweak the exposure when you process raw files, it’s effectively another form of exposure compensation. You can’t change the aperture, shutter speed or ISO, so you’ll need to choose these settings when you take the picture.

    You can make an image brighter or darker overall using the ‘Exposure’ slider in the likes of Adobe Camera Raw, but you’ll still need a file that offers a suitable amount of detail to begin with.

    You won’t be able to rescue seriously overexposed highlights, and pushing the exposure level to reveal detail in an extremely underexposed picture will degrade image quality.

    PAGE 1: Common questions about using exposure compensation
    PAGE 2: How much exposure compensation should I use?
    PAGE 3: How to control your camera’s exposure compensation
    PAGE 4: What is highlight alert?
    PAGE 5: 3 ways your camera’s auto exposure can get it wrong

    READ MORE

    10 common camera mistakes every photographer makes
    Photography Basics: the No. 1 cheat sheet for metering and exposure
    Expose to the right: the camera technique every landscape photographer must know
    3 exposure techniques every beginner must know (and when you should use them)


    Posted on Thursday, June 27th, 2013 at 12:01 am under Photography Tips.

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