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The Holy Trinity of Photography: Shutter speed, Aperture and ISO

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Many people have the misconception that the automatic function on your camera is there to use as a standard setting. Well, I beg to differ. Automatic is great when you’re still learning, but if you want to take your pictures to a professional level, I suggest you start shooting on manual.  Pitch this blog post to any professional photographer and they’ll probably laugh in your face. However, because this is second nature to them, they often forget how important it is to know and thoroughly understand the three fundamentals. Once you grasp these concepts, you’ll be one step closer to taking the perfect picture and once mastered, it opens you up to a world of photographic creativity. Keep reading this blog post to gain a deeper and clearer understanding of the Holy Trinity of Photography: Shutter speed, Aperture and ISO. That being said, you don’t become a LEGENDARY photographer by following the rules. After I’ve explained the Holy Trinity, I’ll give you some tips on how to creatively bend the rules.


  1. ISO


ISO, strangely stands for- International Standards Organization. Whilst it has nothing to do with the United Nations, it is still of paramount importance to the photography world. Before attempting to take a shot, observe your environment to adjust your ISO accordingly. The ISO in digital photography measures the sensitivity of the image sensor. This will essentially determine the size of the grain (millions and millions of dots that make up a picture). The bigger the grain, the less sensitive to light. The smaller the grain, the more sensitive to light. The lower the ISO number (1/100), the less light is taken in and finer the grain of the image. This setting will be useful in well-lit/ bright scenarios. The higher the ISO number, the more light will be taken in making the grain of the image a lot bigger. This is useful in darker/low light environments. This is why noise, which is the larger grains on an image, is commonly found with light compensation in low light environments.


On the digital photography school blog, Darren Rowse suggests asking four questions when preparing to set the ISO.


What you really need to know: Use a lower ISO for well-lit/bright areas and use a higher ISO for darker environments.


  1. Aperture


There are two main aspects to aperture: lighting and depth of field. Think about the lighting aspect of aperture like this: aperture, measured in “f-stops”, is like your eye. When you’re in a dark room, your pupil expands to allow more light in. When you’re in a well-lit room, your pupil contracts to restrict the amount of light coming in. Depending on the way you set it, the aperture determines how much light is being received by expanding or contracting the hole made by the shutter. When you release the shutter, a hole opens up to capture a glimpse of the scene you are shooting. The aperture controls the size of that hole, in turn, controlling the amount of light the camera absorbs. The thing that often confuses photography beginners is that the large F-stops (where more light comes in and the hole is bigger) are given smaller numbers and the small F-stops (where less light comes in and the hole is smaller) are given bigger numbers. It’s seems backward, but you’ll catch on soon enough! Shutter speed also affects the light coming in. This will be explained later in the blog.


The second part to aperture is the depth of field. If you’ve been around the photography scene for a while, you’re probably tire of hearing the term ‘depth of field’. Aperture has a huge effect on the depth of field in a photograph. Depth of field can be understood as the amount of your shot that will be in focus. If you have a large depth of field, a lot of your shot will be in focus, whether it’s near or far away from your camera. The larger your aperture (the smaller your F-stop), the less is in focus and the smaller your aperture (the bigger your F-stop), the more is in focus. The smaller your number, the less is in focus. The bigger your number, the more is in focus. That’s the easiest way to remember it. Check out Digital Photography Schools blog to see a visual demonstration on how the aperture can change the depth of field.


What you really need to know: Low F-stop numbers= large hole and High F-stop numbers= small hole. The higher the F-stop number, the less light is coming in.  


  1. Shutter speed

The about your shutter on your camera as a curtain covering the light sensor. It opens when the camera wants to capture the scene and allows just enough light to hit the image sensor before it closes again, preventing light from coming in. Shutter speed is especially useful when photographing a moving object. It has the ability to create different effects. For example, in sports photography, we want the image to be ‘frozen in action’ to give the viewer an aesthetically pleasing picture to look at. The viewer is able to see every detail in this photo. In order to achieve this effect, the shutter speed has to be extremely quick. Alternatively, if you decrease the shutter speed, it give the effect of movement by creating a motion blur. This will often be used creatively to portray moving cars or waterfalls. See some visual examples on this blog. As mentioned previously, the shutter speed can also determine the amount of light which the camera allows in. This means that the slower your shutter speed, the more light is allowed in. This would be a helpful setting in a dimly lit environment if the object is still. However, the trick here is to balance the aperture and the shutter speed to create a well-balanced picture. If an object in a dim light is moving, it would be better to use a quicker shutter speed and a lower F-stop to allow more light in and still capture your object in a still position. 


Creative ways to bend the rules:


  1. Aperture


  • Creative overexposure by setting your camera on an extremely low F-stop in a well-lit environment

  • The lower the F-stop, the lower the depth of field. The higher the F-stop, the higher your depth of field. This can be used creatively to lead the viewer’s eye to a focal point.


  1. Shutter speed
  • Longer shutter speed gives the illusion of movement and speed which can be used creatively

  • To creatively expose light in a dimly lit environment


These are just a few ways you can bend the rules once you’ve understood the basics of the photography Holy Trinity. Check out this article for more ways to bend the rules creatively. These rules may get confusing at times but experimentation is the most important part of photography. If you understand these basic features separately, linking them should not be much of a problem.

I hope this article has given clarity on some of the fundamentals of photography. Check out the next fundamental “rule of thirds” on our Cameraverse blog.

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