Getting off Auto and the Exposure Triangle


So, you spent a ton of money on a new camera and you’re not pleased with the way it performs when shooting on “Auto”, but you don’t know what the settings on that knob mean? 


Let’s see if I can help you out and explain what the knob selections you need to use are and what they mean. Then I will follow up with an explanation of how these settings relate and function within the exposure triangle. This may sound challenging, but I am going to leave my web browser and the few textbooks I have on the subject closed. 

So, that means no Google and no Ph.D. explanations here. Just simple layman’s terms to hopefully help you get more out of your camera and enjoy capturing images more. Ready? Here we go.


When shooting on Auto the camera is in complete control and you are at its mercy. With a basic understanding of three other modes and some practice, you will find you don’t have a thousand-dollar boat anchor or wheel chock but something that will actually capture great photographs. The modes you need to be operating in are aperture priority indicated by ‘A’ or ‘Av’, shutter priority marked with ‘S’ or ‘Tv’, and finally manual which is universally ‘M’. A fourth setting you need to be aware of is ISO which in simplest terms is a measure of your camera's sensor sensitivity to light. I will explain more a little later.


Now to explain these modes a little bit.


Aperture priority allows you to select the size of the opening in the lens and the ISO setting. The camera's operating system (software) selects the shutter speed.


Shutter priority lets you select how fast the shutter opens and closes as well as the ISO setting. The camera's software selects the best aperture for your selection.


There is also an option available on most if not all digital cameras where you can select auto ISO as well. But I would caution against that most of the time. You will see why when I explain the ISO part in the exposure triangle.


Finally, there is the Manual Mode. In this mode, you are in complete control of all the camera's functions. Sounds scary right? It can be but if you understand the Exposure Triangle and how all these modes relate to each other it can be a haven for some great images.


Now, let’s talk about the Exposure Triangle and how its parts affect your image quality and exposure. The triangle is made up of three components. I guess It wouldn’t be a triangle without them… Those components are ISO, Aperture, and Shutter speed. All three working together in some capacity are responsible for exposure and how your image looks at the end of processing.  It can be the Trinity of Awesomeness when used correctly or the Evil Trinity of Failure when one or all elements are not used correctly. 


Let’s start with the ISO. As mentioned before the ISO is your camera's sensitivity to light. The ISO has a number value ranging from 50 to 12800 and beyond. Most consumer cameras will start at 100 or 200 and end around 12800. These numbers also have an effect on noise or what makes an image look like it was printed over sandpaper. Therefore, the smaller the number the less sensitivity to light and the clearer the image structure or lack of noise. The higher the number the more sensitive to light and noise. What this means then is an ideal ISO for shooting outside on a bright sunny day is going to be between 50 and 400, indoors with a well-lit room 800 to 3200, candlelight 3200, and beyond.


Next up is the Shutter speed. Shutter speeds range from Bulb or 30 seconds to over 1/8000 of a second. These speeds are simply the amount of time the shutter is open and allowing light to reach the sensor.  They also have an effect on the motion within the image or blur.  If your subject is not moving and the light is dim you can use slower shutter speeds with the use of a tripod and have crisp clear images. If your subject is moving then you need the shutter to open and close faster to freeze the action. For example, to capture a child running down the street and freeze their motion on a sunny day you will need a shutter speed somewhere around 1/500 to 1/1250.

Bulb means you have the ability to hold the shutter open as long as you want or need to allow as much light in as possible. This setting is mostly used at night and for astrophotography.


Last is Aperture because it has two roles that can cause confusion. The aperture is the size of the opening in the lens and often referred to as an f-stop. It is usually indicated as an algebraic-looking fraction from f/1.4 to f/32 and beyond. Now, this is the part that can cause confusion for most. Ready? The smaller the f/ number the larger the opening in the lens allowing more light to pass through and reach the sensor. The larger the f/ number the smaller the opening and less light reaching the sensor. In other words, small is big and big is small, got it? 


This setting also has an effect on the depth of field or the linear range within an image that is in focus. The smaller the number the less depth and the larger numbers have greater depth. For example, consider a beautiful model and we have selected f/1.4 and focused on their eyes. The surface of the eyes is sharp and crystal clear but their eyebrows start to appear fuzzy. This is because the smaller the number the shallower the depth of focus or minimum depth of field.   


Now think of a wide-open landscape with a horse about 30 feet away and mountains fifty miles distant. We select an aperture of f/22 and focus on the horse. When we look at the image the horse is in focus and everything beyond to the mountains appears sharp and clear. This is the maximum depth of field at work.


In short, depth of field is what makes the background behind models blurry so eyes rest on them and gorgeous landscapes make us wish we could be there. 


Below is the Exposure Triangle and a graphic representation of how the pieces affect each other.


Get off Auto and explore what each of the settings does as I have discussed them. When you understand how those settings affect the image you will be able to move to manual and take total control when you need to. In all honesty, I shoot almost everything in aperture or shutter priority with my ISO selection. I only shoot in manual when I have complete control of the light or scene.


Get out there and enjoy. Ignite your passion!