Friday, 29 July 2011
The first and most important thing to understand for modern SLR photography, is that to record an image you must have all of the following 6 things.
Light - You cannot have a picture without light in some form or another
Medium - What that light (or image) is recorded onto
Aperture - The hole that that light HAS to pass through
Shutter Speed - The amount of time the light is allowed to pass through the hole
Composition - What is in your picture and how it is composed
Optics* - These are lenses that attach to our SLR camera and focus the light as an image
*It is possible to record an image without optics by letting light pass through a very small aperture, this then effectively focuses the light enough that it can form an image. However optics make it much easier to achieve and also allow us to magnify or reduce the scale of the image.
Here is more detailed breakdown of the six essential requirements to recording an image:
LIGHT – To make a picture you require light, that light may be natural (sunlight/moonlight) or artificial such as a light bulb or flash. Light that our own eyes are sensitive to is called visible light but other creatures and materials are sensitive to non-visible forms of light such as ultraviolet light, infrared or x-ray. We can’t see those forms of light but some animal’s can, although we do have certain materials or mediums that can record them as a photograph.
MEDIUM - Film, digital sensor or special recording material. These materials or mediums are available in different sensitivities which are generally called ISO (film speed) and are what we record or “capture” the light onto.
APERTURE (Av = Aperture Value) – The size of the hole that the light has to pass through to form an
image. An example would be a pinhole camera, this hole focuses the rays of light to form an image on the medium. However to effectively form a high quality image we uses lenses to focus the light and the
adjustable aperture inside the lens controls how much light gets through and how much of this light/image is in focus.
SHUTTER SPEED (Tv = Time Value) – The amount of time the light is allowed to pass through the hole. This provides the ability to freeze action of fast moving subjects by using a fast shutter speed or let objects or motion become blurred by using a slow shutter speed. The time the light is allowed to pass through is usually controlled by a door that opens and closes called a shutter. We can control the time we leave the shutter open for from hours to fractions of a second.
COMPOSITION – What is in your picture and how it is composed. This can also include angle of view, perspective, colour, contrast and your subject.
OPTICS – A lens which focuses the light to a given point on the medium. Depending on the type of lens and its shape and the amount of elements and their space apart will determine if the image is magnified or give a wider view than your eye.