Easy Basic Photography
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Using Exposure Compensation EV+ and EV-
Sometimes your digital camera will produce an image that is too light or too dark. This is because your digital camera light meter can be thrown off
when there is tricky lighting in a scene. The easiest example of when a picture might come out too dark is when you take a picture of someone,
but snow is the most dominant thing in the scene. Your digital camera meter will think there is too much light for an average scene and reduce
the amount of light allowed through the lens and your main subject will come out too dark. (underexposed) On the other hand, if you take a
picture of someone at dusk, the camera meter might think there is not enough light for an average scene and allow too much light into the camera
and the subject will come out too light. (overexposed)
Those are just two examples of when you might want to use your digital camera's Exposure Compensation feature. The purpose of the Exposure
Compensation feature is to adjust the camera's Exposure Value (EV) setting. The Exposure Value is simply the combination of the shutter speed
and aperture setting that your camera's light meter uses to produce a "properly" exposed image. (see the tutorial Exposure Basics for more on
exposure) When you use the camera's exposure compensation feature, you can increase or decrease the amount of light allowed into the camera
during the exposure. A setting of EV+1 will allow more light into the camera during the exposure. A setting of EV+2 will allow even more light
during the exposure. On the other hand, Exposure Compensation settings of EV-1 or EV-2 will decrease the amount of light allowed into the
camera during the exposure. The EV values can also be set in 1/3 increments between EV 0 to EV+2 or EV 0 to EV-2.
Exposure Compensation Camera Meter Suggested Exposure Compensation
EV+1 Exposure EV-1
Different cameras use different methods to set Exposure Compensation. For most basic compact digital cameras, the camera will choose which
shutter speed and aperture will be used when the Exposure Compensation feature is used. However, in most Digital Single Lens Reflex (Digital
SLR) cameras, the user may determine in part how the Exposure Compensation is set.
For instance, a Digital Single Lens Reflex camera user may set the camera to a particular shutter speed and use the Shutter Priority mode. When
the exposure compensation is calculated by the camera, the shutter speed will remain the same and the camera will automatically change the
aperture setting to achieve the desired exposure compensation. When the Aperture Priority Mode is used and a particular aperture is set, the
camera will change the shutter speed to accomplish the desired exposure compensation while leaving the aperture setting constant.
The following shows how the camera settings will change using exposure compensation. We will assume that Aperture F5.6 with a shutter speed
of 1/125 is the exposure suggested by the camera's light meter reading.
When using Shutter Priority: When using Aperture Priority:
EV+2 EV+1 EV-1 EV-2 EV+2 EV+1 EV-1 EV-2
Shutter 1/125 1/125 1/125 1/125 1/125 Aperture F5.6 F5.6 F5.6 F5.6 F5.6
Apetrure F2.8 F4 F5.6 F8 F11 Shutter 1/30 1/60 1/125 1/250 1/500
If you don't set the camera to aperture or shutter priority mode and use the automatic mode, the camera will set the appropriate shutter speed
and aperture for you. If you then decide to use the exposure compensation feature, the camera will use variations of shutter speeds and
apertures to obtain the desired exposure compensation effect.
For those who have cameras with the full manual option, these same effects can be accomplished by changing the aperture and shutter speed
settings manually to get the image exposure you want.
The photos below show a typical example of when you might want to use your Exposure Compensation EV + - feature. In the photo on the left, I
took the picture using the camera's suggested aperture and shutter speed. It seemed a little too light for me, (overexposed) so I set the camera
to EV-1, to make the image a little darker. Don't forget that you can also use the increments between EV +2 and EV-2 to get the effect you want. I
just used EV-1 to keep it simple. Also, the settings may vary, depending on your own particular camera.
Basically, changing the EV for different shots has long been known to photographers as "Bracketing". Bracketing is a useful tool in situations
where the lighting is tricky and you are not sure which exposure setting will give you the best final image.
What about ISO? As you probably know, ISO is part of the Exposure Triangle. (Shutter Speed, Aperture, ISO). Check our tutorial on ISO for more
detailed information. The same principles mentioned above will apply no matter which ISO setting is used. For instance, if you are taking pictures
using an ISO setting of 100 and there is not enough light to produce a good image even when using an exposure of EV+2, then try changing the
ISO setting to 400. This will give you an extra 2 stops of light and you may then be able to get a good exposure using the exposure compensation
feature. The reverse will work in situations when you are trying to photograph brightly lit situations.
Same as everything else when learning photography, knowing when and how to use exposure compensation, along with practice will improve your
photography skills.
Picture taken using camera meter
suggested exposure
suggested exposure
Picture taken with EV-1