Smart Photography

with KARL FEHLAUER THE EXPOSURE TRIANGLE

Welcome back to my latest article on smartphone photography. So far, I have discussed what smartphone (or small sensor) photography is, some techniques for getting better images and how to set up your camera settings in your phone. I hope that you have enjoyed these articles and found them useful.

In this article I will cover what is known as the ‘exposure triangle’ so that you understand how to capture an image with the exposure that you want. Notice I didn’t say ‘the correct or perfect’ exposure but more on this shortly. Smartphones and tablets have revolutionised the way many people take photos, and more photos are taken by these devices every day than any other camera device in the past. By combining a camera with a smartphone (and tablet) it has given instant access to everyone to enable them to take a photo immediately as everyone has at least one (if not more) devices on them at any time. For most people using their smartphone camera, they simply open their camera and take a photo using the camera’s auto settings and are happy with the result as the camera uses computational algorithms to determine what the best exposure settings are before it takes the photo. In most cases the camera ‘gets it right’ based on what it thinks the correct or perfect exposure is (or should be). However, this isn’t always the case and sometimes the images don’t work out or the photographer isn’t happy with the result. Also, there will be a time when some photographers want to be able to create their own image based on what they see, the exposure they want and the mood that they are trying to create. As I mentioned above, there isn’t a ‘correct or perfect’ exposure because each of us has different likes and dislikes and what one person thinks a good exposure is, another may not. Essentially, an image’s exposure can either be over-exposed, under-exposed or somewhere in between. An over-exposed image is usually very bright with lots of detail hidden in the brightest part of the image, whereas an under-exposed image is usually dark with lots of black and detail hidden in the shadows. It is usually easier to recover

Seascape - Albany (Samsung S21).

the detail in an under-exposed image than in an over-exposed image because that detail in the brightest part of the image is usually lost. Many photographers will intentionally under-expose an image to ensure that they have all the detail and can then recover that detail when post processing. For example, when I do my nightscape photography, I will under-expose my images so I can bring out the detail in the night sky/Milky Way. Also, if I am using a flash or external lighting, I will also under-expose the image so I can get the correct exposure I want in post processing. I will cover post processing and some of the apps available to do this in a future article. So, how do you get the correct exposure that you want? Firstly, you need to be in the camera’s manual mode - often called ‘Pro-mode’ ‘Pro’ or ‘Pro-photo’. From there you can set the shutter speed and ISO that you want, remembering that most smartphone cameras have fixed apertures which cannot be adjusted. How do you know what the correct settings are? Simple, this is where the ‘exposure triangle’ comes in and by understanding it, you will have a far better understanding of how to select the correct settings.

The exposure triangle consists of aperture, shutter speed and ISO and by adjusting one or two of these it will create the exposure that you are after. Firstly, let’s talk about aperture. As I have mentioned before, most smartphones have a fixed aperture in their cameras, usually between F1.8 Mushroom - Macro (Samsung S10). to F2.8. Basically, the aperture is the size of the opening in the camera lens that lets the light in and the smaller the number the wider the opening is. So, an aperture of F1.8 will let in a lot of light whereas an aperture of F16 or F20 lets in very little light. Generally, having a wide aperture is usually very good for low light situations, but the size of the sensor comes into play as well and smartphones have very small sensors which does restrict the low light performance somewhat, but in most situations, you can get some very decent images in low light conditions. However, in bright conditions it will let in too much light and as it is a fixed aperture you will need to adjust the shutter speed to reduce the exposure, but more on that shortly. Aperture also affects the ‘depth of field’ (DoF). In its simplest definition, the DoF is that part of the image that is sharp front to back and a wide aperture usually has a very shallow DoF, whereas a small aperture will give you a very sharp image through the image; however, with the fixed wide apertures that smartphones have, generally you will have a shallow DoF but in many cases you may not notice it due to the size of the images on the screen. The second part of the exposure triangle is shutter speed. Shutter speed affects both the motion of the subject in the image and the colour of the background (in particular the colour of the sky). Shutter speed

is measured in seconds or fractions of seconds and is the time that the lens stays open to let the light in. Basically, the faster the shutter speed, the shorter the time the lens is open and the less light that is let in and vice versa, the slower the time, the longer the lens is open and the more light that is let in. Therefore, by using a fast shutter speed and reducing the amount of light coming in, it will freeze motion and darken an image, so if you are photographing a person running, you would use a fast shutter to freeze them, otherwise they would be very blurry. Also, if the image is too bright (or over-exposed) a faster shutter speed will darken the image and balance the exposure. You can also use a fast shutter speed to darken the background,. For example, to make the sky a lot bluer, you would use a fast shutter speed which will make the sky a lot darker. As most smartphones have a very wide fixed aperture you will need to use a very fast shutter speed to balance the exposure of the image and sometimes those speeds may be as fast as 1/4000 of a second. One benefit of using fast shutter speeds is that in most cases your images will be nice and sharp and not blurry, however, using shutters speeds of < 1/40th of a second or longer (i.e. 1 sec, 5 sec, etc.) will introduce blur because it is too hard to hold a camera for too long without moving and therefore you will need to use some sort of tripod to hold the camera still. The last part of the exposure triangle is known as ISO. Simply, ISO means 'International Standards Organisation'. The ISO measures the sensitivity of the camera’s sensor and the smaller the number the less sensitive the sensor is. In very basic terms, ISO is simply a camera setting that will brighten or darken a photo. As you increase your ISO number, your photos will grow progressively brighter. For that reason, ISO can help you capture images in darker environments, or be more flexible about your aperture and shutter speed settings. However, raising your ISO has consequences. A photo taken at too high of an ISO will show a lot of grain, also known as ‘noise’, and might not be usable, therefore, brightening a photo via ISO will always have this as a trade-off. You should only raise your ISO when you are unable to brighten the photo via shutter speed

Three image panorama (Samsung S21).

Kulin camping (Samsung S21).

or aperture instead (for example, if using a longer shutter speed would cause your subject to be blurry). Most smartphone cameras have a very low ISO, for example my Samsung S21 has the lowest setting as ISO 50 which is very good and the highest setting of 3200 and I would only use this in very extreme situations, such as nightscape photography and even then, I would only use 3200 as a last resort as the ‘noise’ is very noticeable. In most situations you would only adjust (increase) the ISO when shooting in low light conditions, such as at night or inside a building, and you need to use a faster shutter speed, otherwise leave it at its lowest setting. So, there you have it - the Exposure Triangle in its simplest terms. Now that you have a better understanding, you can use it to create the exposure that you want in your images. As I have already mentioned, smartphone cameras have a fixed aperture so you can only adjust your shutter speed or ISO and I would advise that in most cases you would use your shutter speed to adjust the exposure in the first instance and only adjust the ISO in low light conditions when you need to use a fast shutter speed. The best way to understand this is to go out and put your camera in ‘Pro’ mode and play around with the shutter speed and ISO to see what the differences are and how they work together to create an image. As they say, practice makes perfect and digital storage is cheap and you can delete the images at the end. Different genres of photography will require different exposure settings. For landscape photography, I use fast shutter speeds and the lowest ISO, whereas for nightscape photography I will use a very slow shutter speed (up to 30 seconds) and an ISO of around 1600-3200 and the smartphone will be on a tripod. In my next article I will discuss white balance (WB) and focus points and how these affect the image, as well as how and when you would need to adjust them. I will also discuss the difference in RAW and JPEG file formats. If you are interested in seeing some examples of my photography with both my Smartphone and DSLR camera systems then checkout my website, Facebook page or my Instagram and Vero accounts – just search for Westralian Images and please leave a comment. Until next time, keep the shiny side up and get out there and take lots of photos.