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A question, Why do we light for photography?

With modern cameras apparently able to "see" in virtually no light (..ahem) a question arose the other day about why we have to add light for photography reasons. I shall now answer this.. 

1) To Illuminate the subject-This sounds obvious, and is, of course, as photography is named after the Greek word photos=light
2) To produce the correct exposure on the film or sensor- see the earlier post about aperture and shutter speed control and making the sensor or film accept the same amount of light
3) To create contrast and depth
4) To create mood

OK, let's start with Illumination
This is obviously the most basic function of lighting. Think of a dark night in a field with no reflected moonlight. It is pitch black and your eyes can see nothing, so you switch on a torch to allow your eyes to register the ground in front of you. Well, a camera sensor works in the same way. The sensor is an electronic panel that has many millions of light sensitive cells on it. The photosensitive cells need to be stimulated by light and in turn, this creates an electrical charge that is converted into a signal. So, in order for a signal to be recorded, there needs to be enough light to make the sensor work correctly. No light=no picture. Simple

Correct exposure
This is controlled through a number of contributing factors including lens aperture, shutter speed, camera filtration, and lighting. You need to introduce enough light onto the subject to allow the camera to perform at its optimum. This means understanding the limitations or 'dynamic range' of a given format or camera.
For example, many cameras can have as much as 8-12 f-stops of dynamic range , that is the difference between resolving detail in both the shadow (dark) area of the scene and the highlight (bright) areas of the scene simultaneously. The human eye can resolve much more than that. It's difficult to measure exactly how much because our eyes adjust so quickly to contrast in a scene, but it is estimated that we can see about 15 f-stops of range in a given scene. The actual number is less relevant than understanding that cameras are much more limited than our eye, and so you have to use lighting to capture the important parts of the scene so that they fall into the 'resolving' capability of the recorded image.

Create contrast
Photography is normally a 2 dimensional medium, yet we experience life in 3 dimensions, with the output of our 2 eyes being continually computed by our brain to experience depth. Setting aside the evolution of 3D shooting and 3D video technology, light is used to create the illusion of a 3rd dimension in 2 dimensional video.
Photographers use light to give the scene a sense of perspective. By creating contrast between shadow and highlight, you give the viewer a sense of depth. A backlight can help "un-stick" a person from the background, hence the need for lighting.

Create Mood
Light colour, light intensity and light quality all contribute to creating mood in a scene. I very much subscribe to the school of thought that believes you should always motivate where light comes from, and use realistic colours that are natural or appear to emulate our environment.

Daylight is fundamentally a cool light with tones that lean towards blue. Artificial light such as a candle or a household tungsten bulb are much more orange in colour and are often referred to as warm lights. Light is measured scientifically in 'Kelvin' using the visible light portion of the electromagnetic spectrum. So, the cooler the light in colour, the higher the number in Kelvin, daylighttherefore is normally measured as 5600K. The warmer the light in colour, the lower the number in Kelvin so a household tungsten bulb, for example, is measured as 3200K.

The digital camera has the ability to set a colour balance and this is measured in degrees Kelvin. So, a daylight camera colour balance is 5600K and a tungsten camera colour balance is 3200K.

Once you understand WHAT it is you are trying to create, you can then look at the HOW to achieve it. That then moves you to consider what the most effective tools will be to 'create' your lighting setup.

Which camera should you now buy?

If you are a newcomer who wants to know more about photography, then deciding on the camera to buy is not that straightforward a business. So, a short multi part guide to explain a few of the things you need to consider.

For a newcomer (and anyone really) it won't take very long to discover there are probably over 100 different models of camera to choose from. Gone are the days when a camera was launched and that camera model was available and continued in production for many years.

There are many different shapes and models designed specifically for particular usage, such as for fun days out by the sea and others designed for the maximum flexibility and aimed at different users.
To make this a bit clearer I have broken down the main considerations for you when buying a camera, and hopefully you will make the correct decision for your individual uses. 

One factor that is certain you will find some cameras limiting and others overly complicated, depending on your starting point. The best thing to do is consider what you want to do then make an informed dcision.


Camera types
The first thing you will probably notice is that there are a number of different basic camera types.


Compact cameras
The smallest ones have a lens which doesn't come off the body, are they are called ‘compact' cameras. Most manufacturers make a variety of different models, and it can be overwhelming to start.
These cameras are designed to be used by people who ‘point-and-shoot' and who like the camera to do all the hard work. They can be set up to calculate all of the variables such as focus and exposure, and have their uses. 
Advantages: The advantages are they are small and light and have everything built in, such as a flash etc. They can be carried all the time for those magic moments to capture, and can have a very high pixel (resolution ) count nowadays.
Disadvantages: Can be fiddly to use, and can take control when you want to do something else creatively. No lens changing is possible, and due to the price can be less robust and lower quality optics.
Price: Mostly under £100, perhaps £200


Compact System cameras
There is a new type of camera is what is called the ‘compact system' camera. The ‘system' part of the title means there is a range of interchangeable lenses and other accessories to that can be changed for different reasons.
Advantages: Interchangeable lenses for different types of photography. Small cameras, and they are designed to be as automatic as possible. They also allow a greater level of flexibility and control.
Disadvantages: Slightly larger and more expensive, so less likely to be carried all the time.
Prices: Start from £250 to approx £1500


DSLRs
The biggest, heaviest and most adaptable cameras on the market are DSLRs (digital single lens reflex). These cameras usually have a large range of lenses and accessories to choose from.

Whist you can set them in full automatic point and shoot mode - (and many people do) - they are primarily produced for photographers who want to take control of every aspect of the picture making process. A camera setting can change the way movement is portrayed, the amount in focus, colour and many other factors besides.

The lenses are generally the best possible, and the functions are all laid out in an easy to use (if potentially mind blowing ) array. An array of lenses can be attached, and full control can be given to the photographer if required.
Advantages : Flexibility, quality and control.
Disadvantages: Weight, Cost, and size. Can be complicated to use if starting out photography. Often superseded within a year or so with a new model, so the urge is to chase the technology and that gets expensive.
Price £400-5000+

I hope that helps you. There is more coming in the near future.
JK

Hello and welcome to my blog. I am John Keedwell, an author, writer of articles, photographer, film and TV cameraman and High Speed imaging capture specialist