Understanding Aperture
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Understanding Aperture

Why is Aperture so Important?

Of all the elements in the magic triumvirate, ISO, Exposure and Aperture I’m increasingly of the opinion that understanding aperture is the most complex and important. And that is why I’m writing this article. I want to focus more on why we benefit creatively from understanding aperture, rather than simply talking about the maths. And I’m as guilty as anyone in putting the science first in my articles, without really getting into the ‘why’.

As you may know if you’re a regular visitor to this site, I acquired a Ricoh GR IIIx a couple of weeks ago for my regular trips to Granada and other cities. The camera takes a bit of getting used to. I’m a lifelong Canon SLR user, currently shooting with a Digital 5D MK IV and a 5Ds. Street photography is very different to landscape photography and although it’s predictable I’m using aperture differently to deal with these different demands.

My experiment with street photography has made me realise that my understanding and use of aperture have been built on my experience of product photography and landscape photography almost exclusively. Street photography, with its more dynamic demands, has opened my eyes a little wider and presented me with a very welcome opportunity to learn more! There’s a lesson there about comfort zones. Be aware of them but push the boundaries until you feel you’re in new territory. Not only will you surprise yourself, but we learn much more quickly when uncomfortable.

The Effects of Aperture

I’m not going to get into hyperfocal distance, or optimising the focal point in a picture, those topics are worthy of an article themselves. Instead I want to focus on the creative use of aperture in broad terms.

Without getting into the maths, the fact is that distance from the subject matters, (a long distance to the subject shot at f/2.8 delivers a deeper depth of field than the same aperture shooting close up.)

Aperture, in addition to letting more or less light into the image, is one of the tools that enables the photographer to dictate where the eye is drawn to in a picture.

26mm f/3.2 1/160sec Handheld

At one extreme, a wide open aperture (f/1.4 to f/4) will remove the focus from the background, concentrating it on the subject. At the other extreme, the smallest aperture (f/16-f/22) reduces the amount of light coming into the sensor and creates much more depth in the picture by everything being in focus. Beware though of the adverse effects of diffraction at the extreme ends of smaller apertures. The middle ground is usually where the area of greatest sharpness is found and can be used creatively to separate larger things from their background eg. Groups of people.

How Understanding Aperture Affects Landscape Photography

Aperture, used creatively, gives us the opportunity to change what an image is about, as well as directing the viewer’s eye.

Take a typical landscape image. There will be a foreground, a middle and a background. If aperture is used to throw the middle and background out of focus then the picture is about the foreground, be it a patch of flowers, rocks or anything else. In this example although the background is brightly lit, the eye settles on the girl in the foreground.

Keeping the foreground in focus and including the middle ground encourages the viewer to explore the middle ground – this effect can be strengthened by the use of leading lines, a pathway or road for example.

Getting everything in focus is often the aim of epic landscape photography, especially panoramas, where the detail in all three areas, front, middle and back encourages the viewer to explore and find their own stories in the image.

Using Aperture in Street Photography

In street photography you don’t have the luxury of fiddling with the camera settings, because often the photographer is reacting to events playing out in front of the camera. This is why I favour the technique of setting my camera to record a scene into which I hope an interesting story will arrive.

This also gives me the opportunity to set my aperture to the best possible setting depending on what story I think is going to develop. Of course this leads to many wasted frames, but the ones that work, work well.

Developing an Understanding of Aperture

We need to get from an acknowledgement and intellectual grasp of the science to a more instinctive place where we know what aperture to use in any given circumstance. This takes time, in my case several years elapsed before I felt I could tell by looking at an image what aperture had been used to within a couple of stops. The only way to develop this level of understanding is by repetition.

Experiment and Play with Aperture

Understanding Aperture Foreground focus
26mm f/5.6 1/160sec Handheld

Experimenting deliberately and often is key to making this process more instinctual. This is the bit where you stop being self-conscious about your photography and start playing with it for the simple joy of exploring. I’m sometimes dismayed at people who pronounce with unflinching confidence that such and such aperture is the best to use for any particular type of photography, because it tells me they don’t know how much they don’t know. (see also the Dunning Kruger Effect). When I taught at the University of North London we used to call that stupid. Don’t be that photographer, never think there is nothing more to learn.

Aperture & Video

You won’t be surprised to find out that Aperture has the same effect on video. However there is one critical deviation from the features we experience in photography. It is not directly connected to the setting we choose for Aperture, but it reduces our options somewhat.

Let me explain.

When using a DSLR (or mirrorless) camera to record video we set the shutter speed to twice the frame rate. For most purposes we’d use 24 fps as a frame rate, unless we wanted to shoot slow motion when it might be 120fps or higher.

At 24fps we’d set the shutter speed to 1/48seconds. This is in most cases slower than the usual rule of thumb for sharp pictures, and crucially, its lets more light into the sensor than say 1/100 sec. The effect of this is to reduce our options in opening up the aperture to get filmic blurred backgrounds, because that lets more light in too. The result, more often than not is an overexposed sequence.

The answer to to this issue is to use ND filters which will, by reducing the amount of light hitting the sensor, allow you to open up the aperture to compensate. The traditional ND filters will work fine but you can also get Variable ND filters which are more convenient as they screw into the front of the lens casing and can be adjusted for changing conditions very quickly by rotating the filter.

Understanding Aperture and Using it Creatively

Once the science is understood in broad terms, a wide aperture equals a shallow depth of field, narrow aperture equals a greater depth of field. We can begin to predict the effect of aperture on a scene. And this will yield better, more deliberate photographs.

Conclusion

To conclude the article, I started out by suggesting that Aperture was the most complex of the three programmable options we find on modern cameras. The reason it is more complex is that the science is defiantly non-intuitive. The widest aperture has the smallest number.

It’s definitely worth experimenting to get a better understanding of the nuances of aperture. It can really help us guide the viewer towards the story we want to tell.

Lastly, check out my article Understanding ISO in Digital Photography to see how ISO fits into the picture.

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