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Aperture; what are you, tell me your secrets!

aperture

noun
1. an opening, hole, or gap.
“the bell ropes passed through apertures in the ceiling”

When you take a picture, you don’t want it to be too dark or too bright, right? The control of that is called exposure. Controlling the exposure means you control how bright/dark the image is. Aperture is one of the three components of exposure. The other two being shutter speed and ISO. Have you ever wanted to know how to blur the background in a photograph? The thing that controls that, is the aperture. It’s not an effect or an Instagram or Photoshop filter, it’s a mechanical movement within the lens. Let’s get into it.

What is aperture?

Aperture literally means a hole, an opening or a gap. A window can be an aperture, a vent or passage can be an aperture. Because we love the English language and all its subtleties, we must wrap context around a word in order to better understand it.

In the context of photography aperture is: “a space through which light passes in an optical or photographic instrument, especially the variable opening by which light enters a camera”

Basically, a hole that opens and closes, controlling the rate at which light can get in.

If you open the back of a film and press the shutter release, or if you remove the lens from the body and look through it, you can see the aperture. The aperture controls the amount of light that can pass through it and consequently, how much light can reach the film or sensor. Aperture size, and therefore brightness, is controlled by the iris diaphragm. The iris is made up of a number of thin, interleaving blades which rotate to make the aperture larger or smaller. Making it smaller reduces the amount of light that can pass through, making it bigger increases the amount of light that can pass through.

Takeaway: what is the aperture? – it’s the hole in the lens that lets in light

what is aperture

What the hell is an F number?

The aperture ring on the lens is calibrated with a series of progressively increasing numbers that can seem confusing at first glance. The series usually starts at 2, 1.8 or 1.4, and increases to 4, 5-6, 8, 11, 16, and perhaps further to 22, or even 32. The numbers, in fact, are far from random, as closer scrutiny reveals; the series double at every other value. f-stops, or f-numbers are a measure of the size of the lens aperture. Each number though, is not the diameter of the aperture, it is the number by which the focal length of the lens must be divided to yield the aperture diameter. The numbers can be written as f/2, f/16 and so on – f being the abbreviation for focal length. For example, when a 50mm lens is set to f/2, the diameter of the aperture is 50/2, or 25mm. When referred to in speech, the numbers become ‘eff-two’ and ’eff-sixteen’ the oblique line is ignored.

The brightness of the image on the film depends on the combination of the aperture size and the focal length of the lens. A large aperture and a long focal length can transmit the same brightness of light as a small aperture and a short focal length.

This may seem like a very complicated way of measuring the power of a lens to transmit light. However, it has certain advantages. Telephoto lenses form a magnified view of the subject, compared with wide-angle or standard lenses. So the light from a given area of the subject is spread over a larger area of film with a telephoto lens. This means there is less light for any given aperture diameter. The f-stop system gets around this problem because it is independent of focal length. An f-number is a ratio, not an actual measurement, so an aperture of f8 on a 50mm lens admits exactly the same amount of light as an aperture of f8 on a 400mm lens.

This is important when changing lenses. A photographer who is switching from one lens to another can maintain the same f-number on both lenses. If the aperture was measured in millimetres. instead of as a numeric ratio, lenses of different focal lengths would need to be set differently.

Why then the curious progression of numbers? Again the choice is quite logical. Each setting of the aperture ring lets through twice as much light as the one before, so with the lens set at f/4, the image on film is twice as bright as at f5.6, and half as bright as f2.8. This doubling/halving sequence may be familiar – shutter speeds increase and decrease in a similar manner.

Note, though, that large f-numbers let through little light, and small f-numbers, such as f2, admit very much more light.

Takeaway:
– Doubling or halving the number, doubles or halves the amount of light getting to the film or sensor.
– Doubling or halving the f number is referred to as; stepping up; stopping down; increasing by a stop; decreasing by a stop

Depth of field

When starting out in photography, this is often one of the first things that people want to be able to achieve because let’s face it, it looks cool.

Only one plane of the subject – the plane of sharp focus – is rendered absolutely pin-sharp. Subjects close to this plane but not actually in it are recorded less sharply, but they do not snap suddenly out of focus. The transition from sharp to unsharp on either side of the plane of sharp focus is gradual and progressive. In effect, subjects are in tolerably sharp focus not just in one plane, but over a range of distances – a zone of sharp focus. The depth of this zone is known as the depth of field.

Depth of field is directly proportional to aperture, and the depth of the field of focus is at its most shallow at wide apertures. Stopping the lens down to smaller apertures increases depth of field, bringing more of the subject into focus.

When you need the entire image to be sharp, you need to stop the lens down to a small aperture, such as f11 or 16. However, great depth of field is not always desirable, and a photographer may deliberately choose a wide aperture to reduce the depth of field – perhaps to blur an unsightly background behind a portrait subject.

Aperture is not the only factor that influences depth of field. Focal length and subject distance do too. Long focal length lenses (see lens types) have shallower depths of field, and wide-angle lenses more depth of field. This is because long lenses compress perspective and make objects appear closer together.

Takeaway:
Depth of field is how much of the image is in focus
Changing the aperture changes the depth of field
Small apertures – deep plane of focus
Large apertures – shallow plane of focus
Small apertures – good for landscape
Large apertures – good for indoors/lowlight and blurring the background

Estimating depth of field

On SLR cameras, the lens is set to full aperture until immediately before exposure, the purpose of this is to let as much light into the viewfinder as possible. If it adjusted the light levels as you changed the aperture the viewfinder would become too dark or too bright and composing the subject would become difficult. Cameras have what is called a depth of field preview button. It varies in location depending on the camera manufacturer, see the instructions to find yours. This will set the lens to the aperture selected to give a more accurate depiction of the final image. Personally I’ve never found this particularly useful, but what is really useful is the markings on the lens itself which allow you to calculate depth of field relative to distance.

Hyperfocal distance 

You may have seen that your lens has a little infinity mark on it. When focussed to infinity, the middle ground of your photograph will be in focus, however the potential depth of field at the other end of the scale is wasted because nothing can go beyond infinity. The wasted part of the depth of field can be put to use by positioning the infinity symbol opposite the depth of field marking for the chosen aperture. The entire zone of sharp focus will then be on the near side of infinity and more of the picture will be sharp.

Summary
what is the aperture? -it’s the hole in the lens that lets in light

What’s an f number? What’s a stop?
– The scale of f/numbers (or stops) progresses like this: f/1, f/2, f/4, f/8, f/16, f/32, f/64, f/128,
– Doubling or halving the number, doubles or halves the amount of light getting to the film or sensor.
– Doubling or halving the f number is referred to as; stepping up; stopping down; increasing by a stop; decreasing by a stop

Depth of field

Depth of field is how much of the image is in focus
Changing the aperture changes the depth of field
Small apertures – everything is in focus
large apertures – very little is in focus
Small apertures – good for landscape
large apertures – good for indoors/lowlight and blurring the background

Where to next?

Camera modes: Aperture Priority – you set the aperture, the camera does the rest.

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Advanced Composition Techniques

Alignment is a mechanism for composing an image that has prominent lines, concentrating on this aims to align two or more of these lines, for example on an office building, aligning the top of the building with the frame emphasises the geometry. With the photographer choosing how to present objects, the edge of the frame can have a major effect and influence on the image. A way to convey strength in composition when concentrating on frame dynamics and alignment is by analysing the horizontal and vertical borders. The corners contribute strongly to the design and directional flow of the photograph; utilising the angular momentum of straight lines can move the viewers eye in a particular direction across the image, this is particularly useful when photographing buildings.

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Contrast plays the biggest role in defining lines visually; contrast between light and shade and between areas of different colour aids composition and directional flow. Specifically with architecture the dynamic lines are an important feature to emphasise due to the direction and movement along their length and height. When composing an image of a building it will automatically become more natural and inviting because it will compare the angle and length.

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Horizontal lines, for instance, have a more tranquil effect than diagonal lines as they lead the eye in a single direction naturally from left to right. Zig-zags can be exciting, but also disruptive to the flow of an image as it breaks up the natural line that the eye will take. Bold lines can express strength whereas thin, curving lines suggest delicacy.

‘in illustration a line is often the first mark made, in photography it occurs less obviously and usually by implication, in respect it is similar to the way we actually see the world, where most lines are in fact edges’ .

I want to experiment with lines and how the eye can be led around a photograph through the photographers use of dynamics. I feel that Andre Kertez employs this well as he uses dynamics strongly within his work.

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Henri Cartier Bresson also incorporates a lot of shadows within his photography, but more specifically tries to capture the living moment, the peak of the entertainment and action going on in the world; despite it being the peak it can sometimes be the most tranquil moment captured due to the stance people are in and  additionally their expressions. Bresson also focuses his work on angles and how the whole frame will lead the eye to a main subject of focus, for example the stairs leading to the man riding his bike.

Alignment within photography concentrates on the arrangements of objects and lines in relative positions, frame dynamics however concentrates on utilising the setting to create frames within frames. View point is also integral to composition when photographing architecture. Photographing buildings from below causes the lines of the building to converge inwards, this can aid the emphasis of the image as it creates a vanishing point. My aim is to explore both the setting and the subject within the frame; placing compositional emphasis on the use of leading lines whilst simultaneously consciously waiting for the decisive moment to occur with that frame.

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Street Photography London

I like Joel Meyerowitz, he seems to love life. His philosophy always makes me happy because of it’s simplicity – ‘what you put in the frame, determines the photograph’. He seems to approach his work from a philosophical point of view as much as a literal, image based one. The real world continues outside of the frame, whatever you choose to put in it, immediately become relevant. Joel shoots on a Leica, which he says is the finer instrument out of that and an SLR. This is due to the fact that an SLR blocks your second eye, whereas with a Leica your other eye is able to see whats coming. I’d never considered it before, but this must be a huge advantage in terms of timing.

I’d like to attempt street photography with a waist level viewfinder and compare the outcomes. I wonder if the physical process of looking at the world through a lower prism would help remove the fear factor associated with looking at strangers. I have grown to love the street photography genre as it has shown me a new type of present that exists only in the photograph. In the photograph it is always the present. I have always been drawn to the notion that life continued after these moments, without the camera, there is no picture.

Forced Narrative

Shooting at a lower angle with a longer lens helped isolate strangers walking by. The two Cindy Sherman style images were shot at 300mm, exaggerating depth of field. The panoramic crop was inspired by Tarantino’s recent film the hateful 8. The essence of the crop brings about a dramatic, filmic quality. It also draws the viewer into the face. It pulls the elements of the frame together and forces a relationship that isn’t really there. This is perfectly demonstrated in the image at the bottom. Two women of different ages, crossing paths in the street. No relationship, no knowledge of each other. Bring them together in the frame, they almost look Photoshopped. The frame however forces the viewer to consider the relationship, developing a narrative that doesn’t exist.

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Street Photography

Street photography has got to be one of the hardest disciplines in photography. Forget complex studio lighting techniques or advanced composition – all of these things can be taught. Holding a camera, looking a stranger in the eye and taking the picture – there’s no lessons for that. In that moment, invading someones personal space for your own gain. Will they freak out, swear, try and hit you? Who knows. But the struggle for our art is real, the fear is real. Maybe photographers love it for the rush, the fear of being caught?

Garry Winogrand had an interesting approach to street photography. In this video at 4:52 you can see exactly what he does to get close to people. In short, he pretends he’s and idiot. It’s as if this is an attempt to disarm the subject in front of him, a clueless man with a camera is no harm and we can continue with our conversation. His mantra of ‘I know what I’m photographing is interesting, but I haven’t seen the pictures yet’ leaves me conflicted. Of course there will always be an element of chance to street photography, but there is a definite formula for a good photograph. Composition, timing, lighting – one must have these key elements to make an interesting image, maybe I’m being too much of a purist and not embracing the love of chance. I do however like his comment ‘I like to see what things look like photographed’. Through all my reservations about chance, this has always stuck with me. Seeing the world with your eyes will always be completely different to how the photograph represents that moment, the magic of not only street photography, but photography in general, will always exist in that unknown.

Best place to practice street photography – The London Marathon

Every year men and women from all walks of life drag themselves through a grueling 26 mile run – at least that’s what their faces say. This is a perfect opportunity to try out photographing strangers as they are completely distracted. The crowds are dense, the noise booming and their are cameras everywhere – people expect to be photographed. That’s where you come in. Set your shutter speeds fast and get shooting. Every type of facial expression, from desire to fear can be captured in a twenty minute period. Your focusing skills will be tested as well as your ability to adapt with crowds and changing light. Something that was almost unexpected from this experience was how it teaches you to see a scene as a whole. The temptation is to single out an individual from the crowd, but you can train yourself to see the scene as a whole. With people running right in front of you it can also help develop depth within your photographs. Here’s a selection from 2016, some are better than others, but the experience is incredibly valuable.

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