First of all remember that photography means “drawing with light” (in Greek photos= light and Graphe= drawing) and as in drawing you need a few different tools to get an image, different kind of pens, papers, technics ...In photography one of these ensemble of tools is called the "Exposure controls".
It s really hard to grab the concepts & rules and even harder to use them in practice. However you CANNOT study photography without fully understand and use these Exposure controls. But once you will understand them, you ll be fine and free to take ANY photographs you ll have in your mind !!!
First comes the sensitivity called film speed for film cameras or ISO for Digital cameras:
The film speed is the rate at which a film is able to capture or react to light. It is usually rated as ASA/ISO and is easily obtainable from 100 ASA/ISO (slow When is really bright ) to 3200 ASA/ISO (really fast when it s really dark ).As I told you more your ISO is High more you ll have grain which affect the quality of your print. A contrario more your ISO is low greater the quality of your picture will be.
Then the Shutter speed:
Shutter speed determines the fraction of a second that the shutter remains open. It thus controls the duration of time for which light is allowed to fall on the film. This is a series of numbers that is usually as follows: B 1 2 4 8 15 30 60 125 250 500 1000 2000...etc.
Slow shutter speeds sometimes record blurred images either because the camera shakes, vibrates, or because the subject moves. The former is called camera shake and the latter is called motion blur. Quicker shutter speeds record images "frozen in time", and would be used for action or sports shots.
F stop and Aperture
As I showed you with a film camera, the Aperture is the eye of the camera.Aperture determines the amount of light I ll let through the lens. Aperture specically refers to the diameter of the aperture stop.
The real question is: why do we care about f stops? Why not just have a great big hole and let as much light fall onto the film as possible?
Because a larger aperture gives a smaller depth of field.
Depth of Field: Depth of field is the distance, front and back, that is the in focus on the image from whatever we are “hard” focused on. A small f stop (big hole, small number like f 1.8) requires a faster shutter speed so the film does not have as much time to record detail (focus) on object in front of or behind the subject we are focused on. A large f stop (small hole, big number like f 22) allows the light through more slowly so we have to use a longer shutter speed to get the right exposure.
Next week we are going to carry on with exercices on exposure controls and hopefully finalise your first set-up photographs !
