Photo Glossary - 10 - Macro Photography

Put simply macro is taking photos of very small things. True macro photography requires a magnification of 1x (or a ratio of 1:1), in other words you must be able to fill your entire photograph with something the same size as your camera’s sensor. In order to achieve this you need specialised equipment such as a dedicated macro lens for an SLR camera or a magnifying attachment for a compact.

This does not mean however that you need expensive kit if you want to take photographs of small things. Almost every compact camera will have a macro mode (normally represented by a flower) which allows your lens to focus closer than normal. It may not give you true 1:1 but it will definitely get you close enough to take some interesting shots. Just remember to turn the mode off before trying to take normal photographs again!

Macro photography has its own challenges. Because your subject is so close to the camera you will find that the photographs will have very shallow depth of field. The depth of field and proximity also mean that it is very susceptible to movement. Ideally you want to shoot with a small aperture and fast shutter speed, which means that you need a lot of light if you want the shot to be sharp and in focus. Alternatively you can use a tripod, which is cumbersome to move around (particularly when chasing bugs) but gives you a lot more control.

Photo Glossary - 08 - Focus Locking

Most cameras give us the option of locking the focus before composing a photo.  This is usually done by pressing the shutter button in half way, holding it in place while you compose and then pushing it in fully to take the photo. 

Suppose that you wanted maximum control of your photograph and had set your camera to focus on the object in the centre of the frame, rather than focussing intelligently.  If you were taking a photo of two people with a small gap between them the camera would focus through the gap on what ever was behind them.  They would be out of focus and the background in focus.  With focus lock you can point the camera at one of the people, push the button in half way as you compose the  photo to include both of them and then push the button all the way in to take the photo.

Photo Glossary - 07 - Depth of Field

Objects that are not on the focal plane (i.e. closer to or further away from the camera than the focal point is) will always be out of focus.  The further away from the focal plane an object is, the more out of focus it will be.  Objects close to the focal plane will appear to be in focus for the purposes of the photograph.  The distance from the closest object that appears to be in focus to the furthest object that appears to be in focus is called the depth of field.

There are three factors that affect the depth of field of a photograph:

 1.       Aperture of the lens – a large aperture will produce a shallow depth of field and a small aperture will produce a deep depth of field.

 2.       Focal Length of the lens – a long lens (zoomed in) will produce a shallow depth of field while a wide lens (zoomed out) will produce a deep depth of field.
 3.       Distance to the Focal Plane – Focussing close to the camera will produce a shallow depth of field, while focussing far from the camera will produce a deep depth of field.

A deep depth of field is useful when you want to capture an entire scene, for example in landscape photography.  A shallow depth of field is useful when you want to draw attention to your subject only, for example in portrait or wildlife photography.

Additional Info

Although the following doesn’t strictly change the depth of field, it allows you to get the most out of the depth of field that you do have.  Strictly speaking, depth of field is a measure of what distance an object can be from the focal point while remaining in focus.  What we really see when we look at a photo however is the apparent depth of field, which is influenced more by the difference between the sharpest and softest areas of the photo, than the actual, technical depth of field.
  

The secret to manipulating the apparent depth of field is in controlling the distances from your camera to your subject and from your camera to the background.  In fact it’s the ratio between the two distances that matters.
  

In order to get an apparently shallow depth of field put your subject close to the camera with the background far behind it.  The bigger the ratio between the distances, the more out of focus the background will be and the shallower the apparent depth of field.  The narrowest depth of field can be obtained by focussing on either the closest or furthest object in the photo.

In order to get an apparently deep depth of field put your subject far from your camera and close to the background.  The smaller the ratio between the distances the less out of focus the background will be and the deeper the apparent depth of field.

The widest depth of field can generally be obtained by focussing at about 2/3 of the distance between your camera and the furthest object in the photo. 

Photo Glossary - 06 - Focal Point/Focal Plane

Focal Point

Focal point has two meanings in photography.
Optical Focal Point is the point of the photo that is in sharpest focus.
Artistic Focal Point is a point of concentration in the photograph that draws the attention of the viewer.
It is quite common for the two focal points to be on the same point in the photograph, for instance the eye or a bird, the centre of a flower or the face of a person in a portrait.

Focal Plane

The focal plane is an imaginary plane that passes through the optical focal point of a lens.  What that means is that everything that is the same distance away from the camera as the optical focal point will also be in focus.  Everything closer to the camera and everything further from the camera will be out of focus.  The degree to which they are out of focus is called the depth of field.

Note:The camera’s sensor is placed on a second focal plane inside the camera, sometimes called the sensor plane.