Photography News | Issue 39 | absolutephoto.com Technique 75 Camera School PART 4 Here we lift the lid on all things camera related, showing how to get better results from your CSC or DSLR and providing all the info you don’t find in the manual. So, stick with us and you’ll soon be wielding your camera like a pro. This month, how exposure compensation can improve on the camera’s metering...
Words & pictures by Kingsley Singleton
When you’re shooting in any of the semi- automatic exposure modes – aperture- priority (A/Av) or shutter-priority (S/Tv) – the exposure settings that the camera picks are based on your chosen metering mode. So, in aperture-priority mode, the shutter speed is generated by the camera, based on the metering; in shutter-priority the aperture would be decided in the camera. In program, which is fully auto, both are decided by the camera based on the metering mode. If you want a little more control you can use exposure compensation. Exposure compensation alters the exposure setting that’s controlled by the camera, so if you apply exposure compensation in aperture-priority mode you’ll be altering the shutter speed set by the camera; in shutter-priority mode you’ll be altering the aperture setting as set by the camera. In program mode, exposure compensation affects both the aperture and the shutter speed at the same time. Taking control of the exposure So, why would you want more control over the exposure settings that the camera has picked? Well, despite how goodmodern cameras are at metering a scene, they do still get confused by some shooting situations. Due to the way that metering systems are calibrated to assume there’s a common level of reflectance in a scene (see last month), predominantly light or dark scenes will often cause them to under or overexpose the picture, respectively. That’s where exposure compensation comes in. So, if you know that a dark scene, like a candle-lit interior, is going to have the camera overexposing, you can dial in some negative exposure compensation (like -0.3, -0.7 or -1.0EV) to make the frame darker. Likewise, if you know that a very light scene, like a snowy field, is going to make the camera underexpose you can set some positive exposure compensation (like +0.3, +0.7 or +1.0EV). You can also use exposure compensation for creative effects, so that you’re deliberately under or overexposing a scene to give it a completely different look (see panel). Stops and go But where do those numbers come from,
Exposure asmetered
Exposure at +0.7EV
Use exposure compensation for better sunsets
Asmetered
How to use exposure compensation Exposure compensation is usually found via a +/- button on the camera body, or on compacts via a similar icon on screen. Some cameras like Canon’s EOS 5D use a large dial on the rear, while cameras with retro designs like the Olympus OM-D bodies and Fujifilm X-series cameras use dedicated dials. When the button is pressed an exposure bar will appear, either within the viewfinder or on screen showing how much exposure compensation has been entered. The amount of compensation is adjusted by turning one of the main control dials and how much you can add depends on the camera model, but it’s often +/-3.0EV or +/-5.0EV. Make sure you switch the exposure compensation off after you’ve used it or you’ll end up applying it to all subsequent exposures and possibly not getting the results you want. If you need to go beyond the amount of exposure compensation offered by your camera (which is pretty unlikely), you’ll need to switch to manual mode and input the shutter speed and aperture independently, to under or overexpose the picture further.
and how much exposure compensation do you need? Like the other exposure settings, exposure compensation is counted in stops, so 0.3EV equates to a third of a stop, 0.7EV to two thirds of a stop and 1.0 to a full stop. EV simply stands for exposure value. Therefore, say your metered exposure in aperture-priority is 1/125sec at f/5.6; if you entered +0.3EV you’d end up with 1/100sec at f/5.6, and +0.7EV or +1.0EV would give you 1/80sec and 1/60sec – all of which lighten the resulting image. Conversely, using -0.3, -0.7, or -1.0EV would give you 1/160sec, 1/200sec or 1/250sec, and therefore a darker image. If your camera’s exposure settings are set up to work in½ stops, you’ll have 0.5, 1.0, 1.5EV and so on. As to how much exposure compensation you need, it depends entirely on the subject and the look you want to create, but often +/-1.0EV is enough to make dark or light subjects look more natural. If you’re using a mirrorless camera or using a live view mode you’ll usually see the image lighten or darken in the viewfinder or on screen as exposure compensation is applied.
-2.0EV
NEXTMONTH How your aperture choice controls depth-of-field.
Another instance where exposure compensation is useful is when shooting sunsets. As metered, the image can look a bit washed out as the camera tries to get a good exposure for the highlights and shadows, often failing on both scores. But try altering the metered exposure settings by -1.0 or -2.0EV and you’ll find that colours are more natural and intense looking than the regular shot.
Your choice Using exposure compensation biases the metered exposure settings as chosen by the camera. So, in the pics above, this frosty scene caused the camera to underexpose; but with some positive exposure compensation it’s fine.
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