Apertures

As far as photography goes aperture is one of the most important factors. We cover this topic extensively in our Online Photography Courses.

Its relationship with shutter speed is one so intrinsic and categorical that to lose one would render the other worthless. That combination between exposure time and exposure sensitivity is at the very heart of every camera that has ever existed, from the first pinhole to the high-end DSLR’s of today. This is all based on one of the most complex and wonderful biological traits, not just in humans but also in almost all animals on earth – the eye.

This month we’re going to be recapping what Aperture is and how it works, but we’ll also be taking a look at the effects of different apertures and straighten out some myths about when these apertures should be used.

What is Aperture?

Aperture is the name given to the hole in your lens, which allows the light to enter. Different lenses have different apertures, which determine the amount of light that can enter, via a contraction or expansion of this ‘hole’, exactly like the pupil of our eye.

The more light we have, the smaller we can allow the aperture to be. The less light we have, the wider we would want it.

Why is Aperture Important?

Controlling the amount of light that enters the lens is essential for a well-exposed photograph. Too much light and we get overexposure. Too little and our shot is underexposed.

The manipulation of how that light enters the lens means we can control the length of time an image needs to expose correctly. The quicker we can do this, the more chance we have of a pin-sharp image. If we weren’t able to control our aperture, we would have no control over the speed at which the image exposes, and the entire photographic spectrum would subsequently be a lot more restricted than it is today.

What are the effects of Aperture?

  1. Shutter Speed

By now we should know that whenever we change our aperture, we can be pretty sure that we need to change our shutter speed. Failing this, the shutter speed will change automatically, depending on what exposure mode we are shooting in. If you have a wider aperture, your shutter speed will be faster. Inversely, the shutter will slow down if that aperture begins to narrow. A failure to change the shutter speed when changing the aperture means a change of light getting into the camera and thus increase or decrease in exposure value.

  1. Depth of field

Aperture also controls what is known as the depth of field. A wider aperture means a shallower DOF. Inversely, a narrower aperture means a deeper or more detailed DOF. Where shallower DOF is concerned, you will notice a quicker loss in sharp focus. The opposite is then true of a narrower aperture.

I now want to spend some time talking about DOF, and it’s relation to various apertures. This is an area of contention with students, I have noticed, with many believing that narrower apertures should exclusively be used for certain types of photography while shying away from wider apertures and shallower DOF altogether!

What is Depth of field?

The depth of field in any image refers to the amount of focus and clarity gained both up to and leading away from your focal point when shooting. There are three main contributors to your depth of field. The first is your distance from your focal point. The second is your focal length and the third, of course, is your aperture.

If we were to shoot a subject that is very close to our lens, the depth of field would be shallower than one with your subject slightly further away. This is down to the acquisition of focus on the subject, which then throws the backdrop out of focus. A subject that is close to that backdrop will mean the backdrop will be less ‘blurry’ than one where the subject is much closer to us.

The science behind this is something we won’t dwell on. But once we know this, we can start to understand how a change in our aperture can affect how quickly these non-focal points retain or start to lose detail.

Shallow Depth of Field

A wider aperture means a shallower depth of field. The image here we can see how a very wide aperture of 1.8 was used, as well as some very close proximity to the subject, to get a very shallow depth of field. You can see how the focus very quickly falls away from the plate and surrounding areas to help us focus on the food in the centre.

When shooting portraits or detail, a wider depth of field is excellent for pulling specific detail out of a narrative. It also has a wonderfully intimate feel as we’re quickly decontextualised from any detail outside of the immediate area.

Deep or Detailed Depth of Field

A narrower aperture means a much deeper depth of field. In the example above we can see just how deep that depth of field can stretch. The focal point was somewhere on the back wall, and an F of 22 gave detailed focus from the focal point right up to the foreground of the image. You can also see how such a narrow aperture also really restricts the way that light exposes, in the overhead lamps. Instead of glowing outwards as we’d expect, the light seeps from the bulbs forming almost a star shape.

What Aperture should I be using and when?

Imagine you’re shooting a magnificent sunset. Imagine way out in the distance the light is catching a rocky mountain scene just before the sun disappears behind the horizon. In front of you and stretching, all the way to this scene is a mass of water. You lift your camera and focus on the distant rocks, cropping out any foreground and most middle-ground interest. What aperture should you use?

This and many others are very common scenes where the wrong aperture is used. It’s straightforward for students to assume that because their subject is a very long way from them, that they need a narrow aperture when this simply isn’t the case.

If there is no hint to that’s around them, no depth to their field of vision, then there is no need to be maxing out the narrowest aperture. In these situations, I will often suggest that half of what the student has used would be applicable and would retain the kind of shutter speed you would want to get a reasonable capture.

When shooting at a very wide aperture, there can be a loss of detail in not just the depth of the image but also in the corners and sides of the frame itself, so finding your middle-ground in these situations is important.

Swap that composition for one where all of that fore and middle ground interest is used and leads the eye in, however, and you’d be looking to use the narrowest aperture you possibly can, to get that full, detailed depth of field.

In some instances, you may want to keep that beautiful, shallow depth of field and also play around with the light glare, atmosphere and purposeful overexposure. This is where your choice in aperture can give you some wonderful creative effects, particularly if you’re shooting in manual mode.

Here, backlighting and a wider aperture were used to keep attention on a warm and intimate scene using a shallower depth of field, while also really exploring how purposeful overexposure can warm up a seemingly everyday scene.

This is just a few ways that aperture can be used when shooting. It is an aspect that covers all areas of photography. Whether it’s for creative or technical use, it will always be there as an inescapable factor in every one of your images, so dive right in and start exploring what it can do for you!

Enrol on an IOP Online Photography Course today to discover more about Apertures and many more photography topics. 

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