As I've previously mentioned my journey to explore and understand Exposure Compensation, I could not for the life of me, fully understand its existence and how it exactly affected my images. Sure, any seasoned photog would find this such an easy concept to understand and would probably chuckle ever so sarcastically to our beginners ignorance - but they've had years of practice and field experience to get to this point. Do not fret, as this to will become second nature to you as well, at the end of this blog.
The first thing you need to know about Exposure Compensation is that it is NOT available in all pro shooting modes (i.e. M,AV,TV,P). To be more specific this feature is not available in "Manual" mode. So what does Exposure Compensation do? This feature will allow you to adjust the exposure manually when your camera tends to underexpose or overexpose your image, since shooting in these modes may often give you an improper exposure.
As a point of interest, each expert shooting mode on your "Mode Dial" takes away one ability that manual mode would otherwise give you full control of. For example, "AV" mode allows you the ability to dial your aperture and ISO to what ever setting you wish, allowing your camera to judge what shutter speed to use automatically. Whereas "TV" mode will allow you to adjust your shutter speed and ISO to whatever setting you wish and allow your camera to adjust the aperture automatically. This is why Exposure Compensation exists, to put back a little more control into your hands when using these expert shooting modes. Although these modes are ideal to use in an array of situations, which I use on a daily basis, they still limit your ability to fully manipulate images to your imagination.
Remember, your camera does not always get it right! This is why Exposure Compensation exist to help you achieve a properly exposed image. Your camera, depending on your model, will typically give priority to the darks and shadows in your image and overexpose your shot in order to bring out details that would otherwise be lost. Now the reverse can happen as well. Your camera may judge that there is to much light and underexpose your image in order to preserve details that would otherwise be lost if the image was overexposed (Tip: reference your Histogram when trying to obtain a proper exposure) Watch this video tutorial on using your Histogram and using different metering modes: http://www.youtube.com/
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