Graduate from Shooting in Auto
Graduate from Shooting in Auto
The temptation, when first picking up a DSLR full of buttons and menu options, is to keep it in Auto and to just rely on one button, the shutter release. But doing so is an injustice to the camera.
In Auto, the camera is going to try and evenly expose the image, using whatever Aperture, Shutter and ISO setting it feels are required. Whilst this sounds like a good idea, because the aim is to get a correctly exposed image, there are very few times when the correct exposure is actually one in which the entire scene is evenly lit. Added to that, you will have no control over the depth of field, how the movement of the subject is frozen, or how much noise is in the image.
Let’s use the classic example of a pale bird with a dark background. The camera won’t know the bird is the important part of the frame, it will just try and even out the exposure between the bird and the dark background.
The end result will be blown highlights in the bird, which is to say, there will be detail lost in the whites, rendering them as solid white. Not only that, but the background will be rendered very light as the camera will think you want to see in to the shadows.
In other words, the camera’s idea of the ‘correct exposure’ would actually be incorrect. To expose for this scene correctly, you would need to set the exposure based on the white of the bird. This would retain detail in the white feathers whilst rendering the background nice and dark, to contrast the bird.
So how do we get out of Auto?
To expose an image and control how much light falls on the sensor, we have control of three things: The Aperture, Shutter Speed and ISO.
Your camera will have three main modes outside of Auto, which in part, relate to these elements we can control. Aperture Priority, Shutter Priority and Manual. Let’s take a look at each of these in more detail.
Aside from controlling how much light enters the camera, the Aperture of the lens also dictates the depth of field within the image. That is, how big the plane of focus is.
Using a large aperture, such as f/2.8, means the lens will let in a lot of light. Using a small aperture, such as f/11, results in less light entering the camera. Lenses with apertures such as f/2.8 are sometimes referred to as ‘fast lenses’, because they allow in more light which means shutter speeds can be kept higher.
Large apertures also result in a shallower depth of field compared to small apertures, where the focus plane is bigger. So this is also something that needs to be factored in when deciding on what aperture setting is best. For example, in one case you may want to isolate your subject from the background by selecting a large aperture. In another case, you may want to use a small aperture to ensure two animals at slightly different distances from you are sharp.
WHEN TO USE APERTURE PRIORITY
Aperture Priority is a semi-automatic mode. Here, you control the aperture and the camera will adjust the Shutter to suit. Care also needs to be taken to adjust the ISO too, but that will be discussed further on.
Setting your camera to this mode is useful when you need full control of the depth of field of the image. For example, if you’re using a telephoto lens and taking a photo of a bird on a stick, and you want it to really pop from the background, you’ll want to use as large an aperture as you can in order to narrow the depth of field. Doing this will help render the background as one smooth indefinable colour, or colours.
By contrast, if you are shooting an environmental shot with a wider angle, where the subject is small in the frame and both the surroundings and animal are equally important, a small depth of field such as f/11 will help to give depth to the image by ensuring more of the scene is sharp.
Like the aperture, the shutter speed also helps control how much light falls on the sensor. Whereas the aperture controls the light coming in to the camera, the shutter speed dictates how long that light is exposed to the sensor.
Much the same with the aperture, the shutter speed also has another important role to play. It allows you to decide if you want your image to freeze motion or emphasis motion. But more than that, if your shutter speed drops too low for the focal length of your lens, it is also the cause for images that suffer from ‘camera shake’.
WHEN TO USE SHUTTER PRIORITY
This is another semi-automatic mode. Here, you control the shutter speed and the camera will work out the Aperture. Again, the ISO also needs to be manually adjusted, but that will be covered a little later.
This is the mode to use when the most important aspect of your photo involves the moment of the subject and how you wish to convert that. For example, if you want to freeze the wings of a bird flying, a high shutter speed of 1/2000s or more may be required. The fast the shutter speed the better frozen any elements moving at high speed will be. The shutter speed needed will varying depending on the speed of the motion.
To contrast that however, you may want to show motion in your image, by dropping your shutter speed very low and panning with the subject. Here, you may need to go as low as 1/10s. Again, exact speeds will vary based on focal length and speed of the subject.
This adjusts the camera sensor’s sensitivity to light. So where the Aperture has let in a predefined amount of light, the Shutter has dictated how long that light hits the sensor, and now the ISO will control how sensitive the sensor is to that light.
Traditionally, the ISO is adjusted manually during either of the previously mentioned semi-auto modes. So that, for example, in Aperture Priority you would set your desired f-stop and then manually adjust the ISO to help balance back the exposure to the level you require whilst the camera adjusts the Shutter for you.
However, there is another semi-auto mode available that works in conjunction with the two above, and it’s a very powerful feature of most modern DSLR’s.
WHEN TO USE AUTO ISO
Enabling this allows your camera to adjust the ISO level whilst working in conjunction with any of the other modes mentioned above (it even works with manual too). This is best used when lighting conditions change quickly, as it takes one less thought process out of the equation allowing you to concentrate on Aperture or Shutter adjustments to achieve your desired result.
Once you have mastered when and how to use the semi-auto modes, it’s time to move in to the realms of manual exposure. Here, you have full control over the Aperture, Shutter and ISO. The camera will only expose for the light as you tell it, giving you the ultimate in creative control.
It does require some practice, because you are adjusting everything, not just one or two things. So, if you decide you want to use a faster shutter speed, but don’t adjust the Aperture to let in more light, or the ISO to increase light sensitivity, the image will start to underexpose as the shutter exposes the sensor to available light for less time.
This can be frustrating initially, however sticking with it will reap rewards as the faster you learn to read the scene in front of you, know what settings you need to achieve the desired image, and then makes those changes quickly, the faster you will improve your understanding of exposure control and with it, creativity within your photos.
MANUAL WITH AUTO ISO
This combination could be argued as one of the most powerful and useful exposure modes to set your camera to. It combines full creative control whilst bringing a little auto adjustment to keep you on track, essentially combining the best of both worlds.
You can select any combination of Aperture and Shutter that is required, and the camera will constantly adjust the ISO to suit. This means for any given style of shot you are trying to create, you know the ISO will always be at the lowest it can be for the given settings you have selected.
It also works with exposure compensation on many models of DSLR, meaning you can still choose to add under or over exposure adjustments to tweak the exposure as required. When you dial in exposure compensation, the ISO will be adjusted either up or down.
It’s not fool proof however and although it works in many situations, especially those with changing light conditions, there will be situations in which switching AUTO ISO off and adjusting it manually will yield better results.