Saturday 29 June 2013

Understanding Exposure: An Introduction to Photography

Understanding Exposure: An Introduction to Photography

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Understanding Exposure: An Introduction to Photography

Posted: 28 Jun 2013 06:35 PM PDT

Mastering photography is like playing a musical instrument. Anyone can make noise on a piano, but to really make music, it is important to read music, learn proper fingering, and practice your scales. Learning how to control exposure is a similar discipline. It’s not exactly fun, but if you ever want to get beyond ‘click and hope for the best’ it is absolutely essential.

What is exposure?

The fundamentals of a camera are very simple: a box with a door (the shutter) that allows light in to burn an image on a light-sensitive surface. The term ‘exposure’ refers to the amount of light to which the film–or the sensor–is exposed.

The most basic photographic errors come down to allowing in too much light (over-exposure/too bright) or too little (under exposure/too dark).

In the photo above you can see the difference between an under-exposed, a properly exposed, and an overexposed image. "Progression of an HDR" captured by Jim Bauer on Flickr.

In the  bottom row of the photo above, you can see the difference between an overexposed, a properly exposed, and an underexposed image.  The top two frames are the same image after a little post production.
“Progression of an HDR” captured by Jim Bauer on Flickr.

A word about light

Understanding exposure makes one marvel at the human eye’s capacity to adjust to the huge differences in light we experience every day. There is around 1,000 times more light outdoors on a bright sunny day than in an averagely lit room indoors. Our eyes can simultaneously process a sunlit lawn and a log in the deep shade of a tree. Cameras are becoming better at this, but the light ‘latitude’ of a sensor is still nowhere near the capabilities of the human eye. To correctly expose the sunlit lawn (i.e. make it appear as it does to the naked eye), the log would be lost in blackness. Correctly exposing the log would leave the lawn a blaze of white.

Shutter speed, aperture, and ISO are the holy trinity of photography. They work in tandem, and to master them is half the battle of becoming a true photographer.

ISO

Don’t worry about what the acronym stands for (it’s ‘International Organization for Standardization’, if you must know). ISO refers to the ‘speed’ at which film–or a sensor–absorbs light. Outdoors on a bright sunny day you would use ISO 100. This is a ‘slow’ ISO but since there is so much light it can absorb it very easily. A ‘fast’ ISO (e.g. 1600) such as you might use at dusk, would be overwhelmed or ‘burnt out’ by so much light. Slow ISOs give minimal grain (for film) or noise (for digital). Generally, this is desirable. Shots taken in low light tend to be grainy or noisy–a trade-off for the ability to shoot when it’s so dark. ISO is the first thing I set on my camera when starting a shoot. Unless the light changes, I can forget about it and move on to aperture.

Using high ISO can cause digital noise in your images."Thingamagoop 2 from Bleep Labs" captured by Kevin Dooley on Flickr.

Using high ISO can cause digital noise in your images.”Thingamagoop 2 from Bleep Labs” captured by Kevin Dooley on Flickr.

Aperture

Put crudely, the aperture is the size of the hole through which the light passes on the way to the sensor. It belongs in the lens rather than the camera body. Making the aperture larger allows in more light; making it smaller allows in less light. Aperture is measured in ‘f stops’ with slightly odd numbers attached. F2.8 is a relatively wide aperture size. If we halve the size and therefore the amount of light, we talk about ‘going down a stop’ to f4. If we go down another stop, we’re at f5.6, etc. The higher the f-stop number, the smaller the diameter of the aperture. Aperture not only controls exposure (how bright/dark an image is) but determines depth of focus – one of the most creative tools available to the photographer. But more on that in a later tutorial.

Shutter speed

The shutter is like a door. Most of the time it’s closed, but every now and then, when we press the shutter button, it opens. The longer it stays open, the more light it lets in. Shutter speeds vary greatly–for portraits, 1/125 of a second is fairly normal. Aside from exposure, shutter speed is important in allowing the photographer to blur or freeze movement. Again, that will be discussed in a later tutorial.

Shutter speed not only allows or blocks light, but it also freezes or blurs motion. "Moment supreme for Kingfishers" captured by Dennis Rademaker. (Click image to see more from Dennis Rademaker.)

Shutter speed not only allows or blocks light, but it also freezes or blurs motion.
“Moment supreme for Kingfishers” captured by Dennis Rademaker. (Click image to see more from Dennis Rademaker.)

Understanding stops

ISO, aperture, and shutter speeds all work on the principle of ‘stops’, a standard measure of light that is most easily tracked in half or double increments.

For ISO and shutter speed, this is fairly straightforward. ISO 400 (a good ISO for a heavily cloudy day) is a stop ‘faster’–or twice as light absorbent–as ISO 200.

A shutter speed of 1/250 is twice as fast 1/125 and therefore lets in half the amount of light.

For aperture, only the numbers are confusing–the principle remains the same. F11 allows in half as much light as f8 since it is one stop ‘smaller’.

If you take a shot that is too dark, you could try increasing the exposure (letting in more light) by a) opening up the aperture by a stop (say f8 to f5.6) or, b) slowing the shutter speed by one stop (eg from 1/500 to 1/250). This way you double the amount of light entering the camera. Either adjustment will result in the same exposure.

If all that has left you a little befuddled, fear not. In the next tutorial, I’ll take another look at exposure–this time how it can be applied in a more practical sense using the different camera modes (M, TV and AV).

About the Author:
I'm a photographer based in Sydney's Inner West (http://www.sydneyportraits.com.au/). While I have always loved portraits, it was the arrival of my son that made me appreciate just how fun and rewarding family photography could be. He's now five and, along with his younger sister, remains my favourite – and at times most challenging – subject. Besides my work as a family photographer, I shoot plenty of weddings as well as documentary work for the likes of the BBC, Marie Claire, The Weekend Australian Magazine, UNICEF, Oxfam and Save the Children.

For Further Training:

There is a popular downloadable multimedia guide with videos that teaches you how to take control over your camera, and get creative and confident with your photography. By combining illustrations, text, photos and video, it will help you get control in no time. Includes a bonus Field Guide—a printable pocket guide with some of the most essential information beautifully laid out inside.

It can be found here: Extremely Essential Camera Skills


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Interesting Photo of the Day: The Tianzi Mountain in China

Posted: 28 Jun 2013 05:14 PM PDT

The Tianzi Mountain in China is no less magnificent from the ground, but some say it is best viewed from a cable car. It takes only a few minutes for visitors to reach the summit where they are greeted by the Tianzi mountain peaks rising one after another. Located in the Northern side of the Wulingyuan Scenic Area, the Tianzi Mountain is at a higher elevation, providing users an expansive view of the Wulingyuan Area.

tianzi mountain china

Tianzi Mountain in China (Click Image to See Full Size)

These sandstone pillars can reach up to 1,200 meters in height. Acrophobics beware!


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This Short Film about the Leica M just Won 5 Awards

Posted: 28 Jun 2013 02:32 PM PDT

You’ve probably seen a lot of camera commercials in your life, but you’ve probably never seen one like this. It’s a minute-and-a-half art film that’s at once enticing, exciting, sexy, and sentimental. It was made to promote Leica’s new black-and-white only model, the digital M-Monochrom, and it recently won five awards at the Cannes Lions Film Festival. These include a Golden Lion in cinematography, a Silver Lion for direction and two Bronze Lions for editing and art direction. These are in addition to the 12 international awards it had previously received (for those of you reading this by email, the short film can be seen here):

The photographer referred to in the video was Robert Capa, a Hungarian combat photojournalist who covered World War II and the Spanish Civil War, among others. He was a co-founder of Magnum Photos – the infamous association of the world’s greatest photographers – along with Henri Cartier-Bresson and others.

Although many details of his life are true (he did indeed die from stepping on a landmine), some Capa advocates argue that the film contains historical inaccuracies or rumors; they claim that he stopped using his Leica in Spain, and was using a Contax and a Nikon at the time of his death during the First Indochina War.

leica camera ad

Nonetheless, the film is a beautiful achievement in its own right. It is narrated by Capa’s old Leica III, and uses low camera angles, sporadic focus, and hectic shots to give the perspective of a lens slung around his neck. It tells (a version of) the story of Capa’s life through stark, gritty, and evocative images which give a palpable sense of passion and of tragedy.

leica camera ad

It was created specially for the opening of the new Leica store in São Paulo, Brazil. Its production was actually not associated with the Leica Camera company at all, and was made independently by Felipe Vellasco of Sentimental Filmes and FNazca / Saatchi & Saatchi (both sites in Portugese). Its title, “Alma”, translates from Portugese (and Spanish, too) as “Soul”.

leica camera ad

In case you’re unfamiliar, Leica is a legendary German manufacturer that is considered the cream of the crop as far as camera production goes. They have been known for their optical superiority and exceptional build quality since they introduced the world’s first practical 35mm camera in 1924.


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The Wrong Way to Photograph Wildlife

Posted: 28 Jun 2013 11:10 AM PDT

If there’s one thing everyone – photographer or not – should know about wild animals, it’s “keep your distance”. This rule goes double when the animal is eating, and triple when their young are nearby. These are the most vulnerable times for an animal, and they will fiercely defend themselves and their food/babies from any swaggering intruder. Case in point: in this clip, taken in the Scottish highlands by videographer Johno Verity, sports photographer Dan Milner tries to photograph a stag deer from about three feet away, and gets a lensful of antler for his audacity (for those of you reading this by email, the video can be seen here):

I suppose the temptation of getting a wide-angle closeup of such a wild beast was too much to resist, but this is exactly the reason that telephoto lenses were invented (well, at least ONE of the reasons). He probably could have stayed inside the car and got his shot, but in our smug sense of human dominance, we can often forget just how dangerous animals really are; they can seriously and even fatally injure a person without hesitation.

Always stay a safe distance from wild animals, and never taunt them the way Milner does at the beginning of the video (Via Imaging Resource). They may not understand your words, but they can probably tell you’re trying to mess with them, and they won’t appreciate it (Via Petapixel). Luckily for Milner, the stag only wanted to warn him – it bucked him and then retreated, and he made it out of there with nothing but a bloody cut on his nose.

wildlife photography

In case you’re trying to decipher his equipment, you’re not crazy – that is a Nikon lens mounted on a Canon body. To be precise, it’s a Canon 1D (can’t make out which version) with a Nikon 14-24mm f/2.8 lens (aka, the opposite of a wildlife lens). According to Milner’s blog, though, the lens actually survived the incident, which is a pretty good endorsement for Nikon’s build quality.


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