Photography lesson 2 - aperture and depth of field

A note on exposure
Exposure refers to the amount of light passing through the lens and reaching the sensor. Too much light and the image will be overexposed, too little and it will be underexposed. It is controlled by two devices on the camera, the aperture and the shutter speed.
The aperture is the hole in the lens through which light passes, and the shutter speed determines for how long the light is allowed to pass through. It is important to understand how both of these work together. Although in ‘auto’ mode the camera will calculate this for you, there are many occasions when you will want to set the exposure manually to achieve a desired affect.

Aperture

The aperture has an ‘iris diaphragm’ that controls its diameter thus letting in more or less light.

The aperture does 2 things:
Firstly, because it controls the amount of light that enters the camera it follows that it controls how light or dark the image is. Secondly, and more interestingly, it controls the amount of the image that is in focus. This is known as ‘depth of field’.

The size of the aperture is referred to in ‘f-stops’ or ‘f-numbers’. The smaller the f-number the larger the aperture and the larger the f-number the smaller the aperture. Thus at f2 the aperture is opened wider then at f9. The typical f-stops on a camera are: f1, f1.4, f2.8, f4, f5.6, f8, f11, f16, f22 etc. Each f-number on the scale lets in twice as much or twice as less light then the next or previous number on the scale. So f1.4 lets in twice as much light as f2.8 and f16 lets in twice as less light then f11.

The affect of the f-stops on the brightness of the image is shown in the following example:



Notice how the images are brighter at lower f-stops (aperture wide open) then at larger f-stops (aperture smaller).

Depth of field

The aperture also affects something called ‘depth of field’ – Depth of field is the amount of the image that is in focus. When you focus your lens on a subject, anything at that same distance will similarly be in focus. Things that are closer to or further from the camera lens will gradually - or drastically - be less sharp. Your camera's aperture controls how large of a zone is acceptably in focus.

At large apertures depth of field will be ‘shallow’ so less of the background will be in focus and at smaller apertures depth of field will be ‘deep’ so more of the background will be in focus.

In this image the tip of the red pencil is sharply in focus and the acceptable focus zone fades quickly so that the other pencils are more and more blurry. This was achieved by using a large camera aperture.


(left to right : f8, f5.6, f2.8)

As you increase the size of the aperture from f8 to f2.8 you'll notice how the heads in the background become more and more out of focus.

What else apart from aperture can affect the depth of field?

Assuming we keep the aperture constant there are 2 other factors that affect the depth of field.
1) Distance of the camera from the subject. Moving the camera closer to the subject will give you a shallow depth of field thus giving you a more blurry background. Moving the camera further away from the subject will give a less out of focus and blurry background.

2) Zoom setting. Assuming aperture and distance of camera from the subject are constant then zooming into a subject will give shallow depth of field and an out of focus background and vice versa.

Thus to summarise, for shallow depth of field:

a) set aperture to maximum
b) move the camera closer to the subject
c) zoom in

When is depth of field useful?

Depth of field is a great creative tool. All images communicate something and what they communicate will depend on where you place the emphasis in the photograph. For example are you trying to give the subject a sense of place by ensuring as much of the background is in focus (deep depth of field – small aperture) or are you trying to isolate the subject from the background so that the eyes are drawn to it? Whatever it is, you must be able to control the depth of field to get the affect you want and controlling the aperture will help you control depth of field.

In portraiture it is considered good stylistic technique to isolate the face from the background. This is achieved by focusing on the eyes and then adjusting the aperture to get the desired depth of field. In the image above, I focused on Alisha and selected a large aperture of f1.8 to blur out the background.



(top left). Notice how shallow the depth of field is here. The focus point is the eyes. Anything behind that focal point and forward of it is out of focus. This has been achieved by using a lens with an aperture of f1.2!

So we can see that shallow depth of field is quite handy when we want to isolate the subject from the background so that the image literally jumps out at you!

What about large depth of field? When is it useful? Answer: landscape photography. When shooting landscapes we want as much of the scenery to be in focus so we select smaller apertures. This will ensure that the whole image from the camera to the background is in focus.

Notice in the image on the left how everything from the wooden post to the mountains is in focus. This was achieved by selecting a smaller aperture (> f9)

Controlling aperture on the camera

When you put your camera in ‘auto’ mode the camera automatically selects the aperture for you. Thus you have no means of controlling depth of field. All SLR cameras and many ‘point and shoots’ have an ‘aperture priority’ mode. In this mode YOU select the aperture and the camera automatically selects the shutter speed to ensure correct exposure. The aperture priority mode is normally designated as ‘Av’ on most cameras.

Another point to note is that the maximum aperture that a camera is capable of is a function of the lens not the camera. The lens of the camera will have on it an f-number. For example the Canon G7 (top right) has f2.8-4.8 written on the front of the lens. This means that the MAXIMUM aperture capability of this lens is between f2.8 - 4.8. When on the mimimum zoom setting the maximum aperture capability of the lens is f2.8. When at maximum zoom the maximum aperture decreases to f4.8 – hence the range.

The great advantage of SLR’s to point and shoots is that you have dedicated lenses with much wider maximum apertures thus allowing you to achieve more pronounced and nicer depth of field affects. In addition, for the more expensive SLR lenses, the maximum aperture stays fixed even when you zoom in. These lenses maintain a fixed maximum aperture throughout the zoom range. But such lenses tend to be more expensive!

In Summary

To achieve nice depth of field:

• select aperture priority mode and ensure the aperture is large (small f-number)
• zoom into the subject to get more shallow depth of field
• move the camera closer or further from the subject for an added layer of control

Photography Lesson 1 - Introduction

There is nothing more beautiful in this world
Then the smiles of innocence these glittering pearls
Amidst a sea of men they shimmer away
Like shards of light
On a summers day

A photographer is like a painter but with a canvass that is far far bigger. How big a canvass you ask? Well as big as the world really. Imagine that! There is nothing out there that is out of bounds save for the reach of your imagination! And nothing should be. So jump and jump as high as you can, even to outer-space if you can. There are of course different genres of photography: fashion, wedding, macro, portrait and landscape to name but a few; but few are as compelling to me as documentary photography. One can describe a place that one has seen, with words; with beautifully constructed precise prose that cuts like a knife and makes the reader feel as if they are sitting amongst it all; but for sheer impact nothing beats a well composed photograph speaking a 1,000 words simultaneously.

Great photographs are those that, like crystalline prose, transport you inside the image; where you can almost smell the stink and hear the sounds and feel the bugs twitching under your feet. That’s what travel and documentary photography should always strive for; teleportation. Teleporting the viewer to the very midst of the chaos and beauty of the far away places you have visited. Allowing people to glimpse the exotic; to smell the foreign; to render the sublime. How do you do that?

Well, there are 2 prongs to photography that are both equally important. There is the technical side of things such as shutter speeds, apertures and depth of field and learning the cameras many functions and buttons and what they do. Then there is the aesthetic side of choosing what to photograph, how to compose the subject in the viewfinder and what the image means. What is the image communicating? What is it saying? The technical aspects can be mastered with practice. The aesthetic elements can also to an extent be learnt but they however require a nurturing of an inner sensitivity to the world; an awareness and appreciation of the poetry, the physical poetry that is out there.

These lessons will attempt to teach both the technical aspects and also give guidance on how to nurture the aesthetic side. This is nothing short of learning how to see the world all over again. For too many of us see the world under a foggy veil, dampened senses and withering appreciation. Without either on your side (technical and aesthetics) your photography will not rise to the heights of self expression that it is capable of. It was Orson Wells who said that “a camera is the eye inside the head of a poet” – so we must all then become poets. Poets with cameras that is!

There is poetry everywhere you turn
Embers of life may wither away and burn
But the poetry of life will always remain
In the images bursting forth
From inside your brain!

But firstly…You don’t have an expensive SLR camera does it matter?

No. SLR (single lens reflex) cameras differ from ‘point and shoots’ in that they have interchangeable lens, give total control over the photographic process, have quicker focusing thus allowing you to capture a moment that a slower point and shoot might miss. SLR image quality is also superior thanks to inherently better optics and sensors. However, many point and shoots nowadays are so good that they feature in the kit bags of many professional photographers. These have professional style features, are cheaper then SLR’s and are more versatile because they are smaller and have a single lens that covers a wide focal range.

If you are thinking of purchasing a point and shoot camera then select one which has ‘aperture and shutter priority’ modes, a focal range (zoom range) that is at-least 30mm on the minimum end and has (for reasons that will be explained later) no more then 10 mega pixels. Since we are on the subject of mega pixels I just want to educate you on a common misconception: contrarary to popular opinion number of pixels has little bearing on quality! – More mega pixels simply means that the image can be enlarged to a greater size. In-fact (let me let you in on a dirty little secret) for point and shoot cameras (not SLRs) more mega pixels generally means inferior image quality ;-)

But the point to take home is that a camera at the end of the day is a tool. The human imagination sets the ultimate limits. You can take wonderful pictures with a simple point and shoot if you know how to use it, if you are aware of its limitations and if you flex those creative muscles. A case example is Henri Cartier-Bresson, one of the world’s foremost street photographers who used to walk around with a basic fixed lens (no zoom) film camera. So as long as your images speak and say something meaningful and are compelling to look at, it doesn't matter what equipment you use.

Coming soon...Photography Class (how to take really great photographs!)

Have you ever wondered why all your photographs suck? Have you ever wondered why your holiday snaps are as lame as a lump of drippy bat droppings?

Well here it is...Everything you've always wanted to know about your camera and photography but have been too f***ing lazy or too stupid to ask i.e. what do all these buttons mean (specially suited for members of the female species). As well as more advanced stuff for the nerds out there:

1) What's all this 'shutter speed' malarky
2) Aperture??
3) Should I give a toss about 'exposure'?
4) ISO, white balance and depth of field
5) Types of lenses and focal lengths
6) The art of composition and the rule of thirds
7) Colour or black and white?
8) Exactly what is it that makes a photograph great?
9) And other highly pertinent stuff that I'm too lazy to think of right now...

Optimus Prime V Megatron (Transformers in disguise)

Optimus Prime ("Freedom is the right of all sentient beings")

Optimus Prime is the leader of the Autobots and leads them in an unceasing battle against the evil Decepticons. His courage and wisdom know no bounds, and he is respected throughout the universe. His weapons include an energy rifle and a blade that extends from his right forearm. He also suffers from bad breath and penile dysfunction (lack of lead in the pencil) for which he has has been prescribed fully-leaded petrol. His long suffering wife (who can blame her) has resorted to having highly passionate and rigorous sex with another machine : the lift, which she claims and I quote 'can go up at my command'

Psychological profiling

One of Prime's most notable characteristics is his commitment to leadership by example, and the avoidance of any hypocrisy in his command, but beyond this he is a straightforward, battlefield General. Prime has also been secretly plagued by self-doubt and a conflicted sense of pacifism that often made him an extremely reluctant warrior, and it was occasionally implied that the conflict with the Decepticons lasted as long as it did primarily due to his unwillingness to take a more aggressive stance. Psychologists claim that he has a tendency to cry when alone at night and that he still sleeps with his teddy bear.

Megatron ("Peace through tyranny")



He is very powerful and utterly ruthless. He is leader of the Decepticons. His primary weapon is an arm-mounted fusion cannon, capable of leveling a city block in one blast. He can also sub-dimensionally link the weapon to a black hole, generating even more powerful anti-matter blasts. However, this ability is almost never used, as it leaves him extremely weak and vulnerable and therefore unable to perform in the bedroom department. Not surprisingly his wife has been seeing another robot : the super-suction 2000 vacuam cleaner (with additional pipes to reach those places other robots cannot reach)

Psychological profiling

There have been several interpretations of his character; some see Megatron as a strategic leader who calls the shots from afar, whilst others see him as a tactical battlefield commander who leads by brutal example. Unlike many other villains in popular fiction, Megatron is not generally depicted as overly chaotic or insane. He is highly aggressive and a megalomaniac but there is usually a consistent rationale behind his actions, albeit that Megatron is often the only one who perceives this. Psychologists have suggested that he had an abusive father who never played with him and that he has a secret fetish for My Little Pony dolls.

History of rivalry

There have been occasions where Megatron displays a personal sense of fair play and even honor, a complexity that is most evident in his relationship with Optimus Prime. There is an unspoken mutual respect between the two leaders, born of each knowing the other better than anyone else. Megatron at times seems to derive enjoyment from the perpetual conflict that exists between them — the pleasure of ending the life of Optimus Prime will be Megatron's and Megatron's alone. In instances such as these, the two have come to face the fact that were it not for their diametrically opposed ideologies and views, in another life the two could be buddies for life and share a pint down the pub for a good ole chinwag.

My Favourite...

If I was a Transformer robot (oh I can only dream) I'd be Megatron. Why? Well apart from the 'My Little Pony' business I feel that he has much better weaponry at his disposal. But also I see Megatron as much more complex and multi-layered. The other reason, and probably the most important, is that as Megatron I'd definitely get more chicks. I mean If I was a chick I'd much rather go out with Megatron then Prime. Chicks dig dangerous guys who have issues, not goody goody two-shoes, time to go to bed by 9 o'clock mummies boys.

When I have a cold...

It all runs south...



Over my lips and into my mouth



Tastes like jam but without the pieces



Think I'm gonna bottle it
And feed it to my nieces...

Catwalk slum (excerpt)

...The city was a mob. A riotous mob of indifference or was it malevolence? Traffic moved somberly because of the mob; which halted at traffic lights where it could breathe. As the lights turned green a torrent of people swept across the road in a bouncing froth of light-weight calicoes and jaded colours as if some invisible sluice gate had been let open and if it wasn’t clapped shut the flow would seep everywhere, becalming the vehicles in an eddy of pedestrians. The sun was out and a blue sky mottled with wisps of white smirked down upon everything; gleaming off the shiny bonnets and the metallic paintwork and shriveling the puddles leftover from last nights rains. The air carried the faint tang of mulberries which jostled with a jungle of bewildering smells all competing for the attention of my nostrils.

The city I came to realise was a distillation pot. A concentrated broth of humanity and thankfully all within comfortable distance as I sat in my taxi. The window was down and with me were my three best friends: Mr Fume, Mr Heat and Mrs Din. The sun burned and the air was thin and meager and the grit from the exhausts was building intimate acquaintances; sticking to my sweat and making me clammy. A giant billboard bottle of ‘Sprite’ loomed overhead; cold, spottled with condensed droplets and promising refreshment and tugging at my parched throat. I was suddenly overcome with an urge for a drink – an ice cold bottle of Sprite for my thirst. I ordered the driver to stop over for a moment. We parked beside a street stall and carried out our transaction through a slit in the window.
The streets were thronged with people traffic on either side. A river thick and miry with domed bamboo hats bobbing up and down like corks. They were a small people of pale skin, black matted hair, petite breasts and pear shaped bums; clad in loose clothing that did nothing to allude to the supine forms underneath. The clothes were or seemed ill-fitting; almost as if everybody wore the same size and all stitched by the same tailor too.

The taxi bumped and ground its way through the narrow streets lined on both sides with buildings that looked like flat pack furniture. The bottom sections were in shade and the tops draped in the warm gauze of morning sunshine. People stood out on the balconies putting their washing out to dry or stretching their muscles. We entered a neighbourhood of rotting bin bags besides rotting buildings. Children playing in the stink with moth eaten faces with eyes set so deep within their orbs; and somewhere within, a flicker of life; a sign of the faint being driving the engine of these desiccated and moribund creatures.

The taxi stopped outside my hotel. ‘Hotel Hanoi IV’ – it too a crestfallen affair; a 4 storey squat concrete building with a baked 'Ryvita' frontage and a brass plaque that read: ‘plenty rooms available’ that was screwed to the pillar - 3 of the 4 screws were missing leaving it dangling morosely. The steps leading to the hotel were in a pose of contorted collapse and wore the look of antiquity lest they should dissolve under my feet and were lined with some sorry looking potted plants; weedy and wizened. It was such a pathetic attempt at comeliness it made me wonder whether the rooms fared any better. I paid the driver and then caught her eye:

She was a lonely creature and was walking down the pavement in such an unexpected elegance of get-up and go that in the first moment I took her for a sort of vision. A creature indeed for you had to be there as witness! Oh! A white dress made translucent by the sun that created a silver haze around her, sunglasses, hair out, so refined, so elegant, so sexy, so gushing! so weird – for she was walking besides the gutter oblivious to the shit and smell around her. It was like watching a shampoo advert. Her demeanour and confidence rebuking the squalor like a slap on the wrist and she had the look of vacant glassiness; then she saw me and her eyes crystalised with recognition followed by a curling of the lips - hence her thoughts so betrayed. It was the sight of this instrument of manly torture so at odds with everything else that had captured my imagination and set forth some unforeseen seismic activity within me. Bewitched, my mind summersaulted to lofty places; beyond the silver lining. I smiled at her as she walked past and nodded my head in acknowledgement. In acknowledgement of what? – Such a fool I was! If ever there was one that walked this earth!

So what was the meaning of it? Acknowledgement of her beauty perhaps? The thing of interest was that she probably lived in this squalour. She was of it! Born and bred in it no doubt. Her beauty and get-up had given her metaphorical wings so to speak so she could fly to a world of make pretend. A world made real by the attitudes and humours of others towards her. And she knew it. For elegance and beauty speak to men’s hearts directly do they not? - Transcending the fabric of our lives and the roots that bind us to the soil. Inspiring feelings that tug at the primordial torrent that seethes within us; elevating a woman to a throne beyond her earthly bounds.

I wondered where she lived. I imagined her bedroom. Probably no larger then a broom cupboard with leprous walls and mildewed ceilings and a few items of furniture; perhaps a small mirror, a little bed and a make shift wardrobe of skeletal frame draped in cloth behind which her few precious items of clothing resided; 2 dresses perhaps that she wore in revolution and then the little window in her room that looked out onto the clotted gutter. The window she looked through every day; her world. I imagined her as a little girl; pretty and naïve playing in the filth. Did she ever dream of escape? Of course she did. Everyone does. I looked around. The whole area wore the face of abject poverty. How many more were there like her I wondered. How many princesses were there in this catwalk of slums...

Currently reading...

Franz Kafka's Metamorphosis. A surreal study of alienation. The opening line of this astonishing short novel personifies the Kafka style : 'When Gregor Samsa awoke one morning from troubled dreams, he found himself changed into a monstrous cockroach in his bed. He lay on his tough, armoured back, and raising his head a little, managed to see..., His numerous legs, pathetically frail by contrast to the rest of him, waved feebly before his eyes'

Hence the auctorial description 'Kafkaesque' used to describe surreal distortion and the feeling of impending doom - that has seeped into the contemporary lexicon. There is another author whose name too has become an auctorial description : 'Orwellian' (George Orwell) used to describe a dystopian nightmare of 'thought-crime' and 'thought-speak' under the auspices of a dark and all consuming cloud of totalitarianism.

So you think you're in control then???

Read Kafka
Read Orwell