Introduction to Photography

Jun 28, 2014 by

Introduction to Photography

The importance of light

As photography is dependent on the reaction of the chemicals on the film to light, it is easy to deduce the importance of light conditions when taking photographs. As light is as important as indicated, one must also be aware that light can be reflected off certain objects, it can be absorbed by others, and it can be refracted by others. One of the problems in photography is that the human eye automatically compensates for specific light conditions. It is for this reason, that we use exposure meters.

 

Most of the cameras also have built in exposure meters to assist the photographer. These exposure meters however sample the complete picture in the viewfinder or only a selected area in the viewfinder depending on the design of the camera. For this reason other exposure meters or different techniques with your own camera can be used to establish the correct settings on your camera.

 

With the exposure meter readings the correct settings can be obtained for the optimum exposure. This is the setting that will allow just the correct amount of light into the camera to expose the film optimally for the reigning light conditions.

 

The figure below shows the basic color which form white light and their complimentary color:

 

Blue       =             Complimentary color   =             Yellow

Red        =             Complimentary color   =             Cyan

Green   =             Complimentary color   =             Magenta

 

rgb

rgb

Measuring light

 

Different methods can be used depending on the situation you are in and the equipment you have available. In the normal situation, the amateur photographer will not have an external exposure meter available. Depending on the composition of the photo the following techniques can be used.

 

Normal (Average brightness or reflection method) – The exposure meter reading on the camera is used as is, for setting on the camera. This will also be the same settings that the camera uses when on auto setting.

 

Tilting method – Tilt the camera of light meter at an angle to prevent a bright background from influencing the readings. Set the camera manually according to the readings and take the photograph from the normal position.

 

Close-up method – If the detail you want to photograph is in shadow and forms part of a composition with bright light, you can get a reading close to the object. The camera should be set manually or if Auto Exposure Lock (AEL) is available on the camera, this feature can be used.

 

Incident light method – Used mainly for studio work. In the photograph below, the close-up method was used to determine the camera settings. The television and the detail in that area is clearly visible, while the windows on both sides show a bright glow.

light

lounge-light

Aperture

 

Also known as the diaphragm or lens opening. The aperture controls the amount of light allowed onto the film. It also influences the depth of field. This is a very important factor to keep in mind and is therefore discussed separately. A camera is equipped with a setting mechanism to control the size of the aperture. (On instant cameras the lens opening and shutter speed are fixed.)

 

The aperture is also referred to as the F-stop or F-number. The F-stop indicates how many times the diameter of the lens opening can by divided into the focal length. In short this means that a smaller lens opening will have a higher F-number. If the photographer want to allow less light into the camera he must use a higher F-number. A higher F-number (smaller aperture) will increase the depth of field.

 

A setting on the F-stop ring is also known as a STOP. Each stop allows exactly half or double the amount of light onto the film, depending on the side to which the setting is changed.

On automatic cameras the aperture can be set automatically according to the prevailing light conditions. This will then be dependent on the light conditions, the shutter speed setting and other settings available on the camera.

For our purposes we will only look at the effect of the aperture setting, while the shutter speed is fixed.

 

The first photo shows the picture taken at optimum exposure settings.

 

tree-optimum exposure

tree-optimum exposure

The second was taken with a smaller aperture (larger F-stop value).

 

tree-smaller aperture

tree-smaller aperture

The third photograph was taken with a larger aperture (smaller F-stop value).

 

tree-larger aperture

tree-larger aperture

Shutter Speed

 

The shutter speed refers to the amount of time that the shutter of the camera is open and the film is exposed to the light.

 

The speeds available on a camera depends on the design of the shutter and camera. Normal settings will include speeds of 1 to 1000. A shutter speed of 1 indicates that the shutter will be open for 1 second. A setting of 2 will indicate that the shutter is open for half (1/2) a second. On a setting 60 the shutter will remain open for one sixtieth (1/60) of a second, etc. Each setting on the shutter speed is also known as a STOP. Each STOP will expose the film for exactly half or double the amount of time, depending on the side to which the setting was done.

 

Handspeed Limit

 

The hand speed limit is the minimum shutter speed at which a photograph can be taken without supporting the camera on a tripod. At lower shutter speeds camera shaking can influence the sharpness of the photo. A safe rule to follow is to ensure that the shutter speed setting is higher than the focal length of the lens. (As an example, for a focal length of 50mm, the shutter speed setting would be 1/60th of a second and for a focal length of 200mm the shutter speed setting would be 1/250th of a second.)

shutter-blur

shutter-blur

In this photograph the photographer did not compensate for the hand speed limit or the flash did not work. The photograph came out blurry and movement is obvious.

Movement

 

If a moving subject is photographed at a high shutter speed (1/500th) the subject will appear as “frozen” on the photograph. If a lower setting is used (1/60th) the subject will appear as “flowing” on the photograph. If the camera is moving as in a moving vehicle, higher shutter speeds should be used. If the lighting conditions do not allow higher shutter speeds, a film with a higher film speed should be used. Moving subjects can also be “frozen” at lower shutter speeds by following the moving subject with the camera (Panning). The background will then have a “flowing” appearance.

shutter-high

shutter-high

In this photograph a high shutter speed was used to produce a frozen image. The water droplets appear to be suspended in the air.

shutter-low

shutter-low

In this photograph a low shutter speed was used to produce a flowing image. One can clearly see the water droplets direction of movement.

Depth of field

 

It is a characteristic of any photographic lens, that only a limited field in front and a limited field behind the focus point will also be in focus on the negative and photograph.

 

 

 

Importance of depth of field

 

If a subject that has depth is photographed, like a wall that stretches away from the camera, the whole subject will be in focus only if it fits into the available depth of field. The depth of field must be more (longer) than the subject photographed. Normally the depth of field cannot be seen through the viewfinder, but on some modern cameras a depth of field preview is available.

 

 

 

The depth of field zone

 

The depth of field covers a zone of one third in front of the focus point and two thirds behind the focus point. In the figure subjects no.2 and no.4 fall inside the zone and will be in focus on the photograph. Subjects no.1 and no.5 fall outside the zone and will be out of focus.If the depth of field zone is enlarged or reduced the relation of 1/3 and 2/3 remains unchanged. Because of this phenomenon, any subject or scene that stretches away from the camera should be photographed by focusing on the end of the first third of the subject or scene.

depth of field

depth of field

The quantity of depth of field

 

The depth of field is influenced by the following factors:

 

The diaphragm or lens opening

The focal length of the lens used

The distance between the lens and the focus point

The influence of these factors on the depth of field is as follows:

 

The smaller the diaphragm the more depth of field (Larger f-STOP number)

The shorter the focal length of the lens used the more the depth of field

The shorter the distance between lens and subject the smaller the depth of field

On lenses with a fixed focal length, there will usually be a depth of field scale and the amount of depth of field can be read from this scale. This is done by focusing the camera on the subject and then reading the distances corresponding to the applicable f-stop setting.

 

Tips

 

To make a portrait photograph stand out it is preferable to decrease the depth of field (lower f-stop value) so that the background “blurs” and does not distract from the main subject.

To get more of your landscape photograph in focus, use a higher f-stop value.

Low f-stop value produces least amount of depth of field . The center of the photograph is in focus whilst the leaves in the foreground and background is out of focus

 

larger depth

larger depth

Large f-stop value produces a large depth of field. Almost everything in the photograph is in focus.

 

larger depth and focus

larger-depth and focus

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