Photography is the art of lighting. Understanding exposure control does not make you a better photographer. But learning and applying manual settings to your exposure will give you more control over how you want your image to be. Like many other new iPhone photographers, you may find the settings in many paid camera apps too overwhelming. Relax, it is entirely okay to use iPhone’s default camera app (though you can’t change exposure settings). But as long as you apply the knowledge when you take a photo, you will eventually form a unique style.
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What Is Exposure?
In simple terms, exposure is the process of letting light through your camera lens onto the digital sensor. This is the very fundamental component in all photography.
How Exposure Works
Technically speaking, there are no golden rules about a perfect exposure. What is perfect for some photographers may not be perfect for others. This is because exposure is a matter of taste. You want to make sure that your photo a balanced exposure so that you can see sufficient details from the brightest to the darkest area of the photo.
The range of light in a photo is described in terms of highlights, shadows, and mid-tones. The highlights of the photo don’t necessarily have the lightest colour. They are where the most light is. In contrast, the shadows are not always the darkest coloured. They are where the least light is. Mid-tones are everything in between.
Finding a Medium
In photographic terms, when the camera sensor doesn’t receive enough light, the image turns out dark. This is described as underexposed. When the camera sensor receives too much light, the image turns out light. This is described as overexposed. The key is to find a ‘medium’ exposure in line with your photographic style, taste and expectations.
When the camera sensor doesn’t receive enough light, the resulting image looks dark and it’s described as underexposed. When the camera sensor receives too much light, the resulting image is bright and described as overexposed. The key is to find an ‘in-between’ exposure that has a pleasing balance of the full range of the photo details.
Exposure Triangle: 3 Factors That Affect Exposure
Three factors equally affect the exposure of every photo you take: aperture, shutter speed and ISO. These factors are often referred to as the ‘exposure triangle’.
Aperture is the opening of the camera lens (technically called an ‘iris’). Aperture refers to the intensity of light. It is measured in ‘f-stops’. The ‘f-stop’ scale looks like this (in 1/3 stops):
A smaller ‘f-stop’ means a larger aperture, while a larger ‘f-stop’ means a smaller aperture. For example, f2.2 is a larger aperture than f22:
Below is a list of the f-stops of iPhone camera lenses:
- iPhone 6/6s/6 Plus/6s Plus: f/2.2 aperture
- iPhone 7: f/2.2 aperture
- iPhone 7 Plus: f/1.8 aperture (wide-angle) and f/2.8 aperture (telephoto)
- iPhone 8: f/1.8 aperture
- iPhone 8 Plus: f/1.8 aperture (wide-angle) and f/2.8 aperture (telephoto)
- iPhone X: f/1.8 aperture (wide-angle) and f/2.4 aperture (telephoto)
What is important to know is that your iPhone camera has a fixed lens, and its overall effect on the exposure triangle is somewhat minimal.
If the aperture refers to the ‘intensity of light’ hitting the camera sensor, then the shutter speed refers to the ‘duration of light’ reaching that same sensor.
If you hand hold your iPhone when shooting a photo, slower shutter speeds (such as 1/2 sec., 1/4 sec., 1/8 sec., 1/15 sec.) are more likely to blur movement. Higher shutter speeds (such as 1/250 sec., 1/500 sec., 1/1000 sec.) are more likely to freeze movement.
In auto mode, the iPhone camera normally picks a low ISO and a higher shutter speed combination. You need to download a more advanced camera app so you can control the shutter speed and/or the ISO.
ISO sets the overall sensitivity of the sensor to light. The higher the ISO setting is, the more sensitive your camera is to light. A lower ISO means a darker picture, but also less noise. A higher ISO gives you a brighter picture, but more noise. Because the iPhone aperture is fixed, the only 2 controls you can make to allow more light through are to adjust the shutter speed and/or the ISO.
Just like shutter speed, the default camera app doesn’t allow you to shoot in manual mode, so you may want to download an app (such as Camera+) to control your shutter speed and ISO. It will take you a while to have a full control of these settings. But when you do, you will be more confident to shoot in different lighting environments.
You can determine exposure in either auto or manual mode. In auto mode, the camera selects the best combination of shutter speed and ISO to give you an optimum exposure. Auto exposure works fine in most bright light situations, but it struggles in low light situations. In most advanced camera apps, you can manually control exposure in shutter priority or full control mode.
However, if you are not quite ready to use shutter speed and ISO settings, you can opt for adjusting the ‘exposure value (EV)’.
Exposure Value (EV)
Exposure value (EV) is a single number that represents the exposure combinations of aperture, shutter speed and ISO. Each EV step equals one stop adjustment of the aperture, shutter speed and ISO. EV is typically used for exposure compensation and bracketing.
+1 EV means to increase exposure by one full stop, thus lightening the image. Conversely, -1 EV means to decrease exposure by one full stop, thus darkening the image.
So these are the basics of exposure. You may think the concept isn’t hard to understand. That’s good for you! But understanding exposure is different from applying it. The science of photography hasn’t changed over the years. Optimum exposure has always been about the exposure triangle – aperture, shutter speed and ISO. However, you might find yourself in a continuing pursuit of mastering the art of exposure.