Intermediate Tutorial 3

A sharp focus is desirable, but out-of-focus effects have their uses. In this tutorial, we look at selecting a point of focus that will ensure the viewer’s gaze is drawn as you intend, and also how to employ blur deliberately – for example, to create the illusion of movement.

3

Using focus & blur for effect

Your eye sees objects in a 3D world by gathering the light reflected from them and turning it into electrical impulses sent to your brain, where they are interpreted as recognisable shapes and tones. Your brain creates the image of what it thinks you are looking at; amazingly, it gets it right most of the time. However, it can be fooled!

Our brains ignore most of the information our eyes see, concentrating on nearer subjects over more distant ones that are unlikely to be a threat or require immediate action; we are unknowingly conditioned this way.

Our eyes have relatively small apertures (the pupils) and thus a large depth of field (DoF) – so we can focus quickly between objects at a distance and those up close, with both within our DoF. The slightly different views received by our two eyes are also used to create depth perception, which we use to train our focus…

Photographs are flat, 2D images, but our eyes try to follow the same rules with them as with the real world. Our conditioned brains apply the same logic in determining points of interest – we are immediately drawn to objects that are in focus.

We use perspective to determine what is near and far, and as nothing is physically moving in photos we look for other indications, such as blur, to determine movement.

Knowing the brain will always follow these rules, we can use cameras to create images that will not only be interesting to look at, but also make viewers notice what we want them to see. In order to create a striking photograph, we have several tools at our disposal – composition, which is covered in the ‘Beginners’ module, and three others that we will examine here: focus point, depth of field and motion blur.


Focus point

When an image is in focus, it is easier to perceive detail because our brains don’t have to work so hard. Therefore, choosing the focus point of an image is very important, as this is naturally where the viewer will be drawn. Depending on the aperture selected, it is possible to have either a large area in focus or a small, specific part – as we learned in the previous tutorial.

For a landscape shot you may want all of the scenery, foreground and background, in focus. For a close-up portrait or macro shot, you will want to control the focus point more precisely. You need to decide which element you want the viewer to notice most.

F2.8 POF Back

The point of focus is set to the spots on the feather.

F2.8 POF Front

The point of focus is set to the feather’s tip.

Take a look at these two shots showing the same subject with different focus points:

Both shots were taken with Auto Focus set to ‘One Point Focus’, allowing for a small part of the image to be chosen as the focus point. For even more precise control, LUMIX G cameras offer ‘Pinpoint Focus’, with a cross-hair you place on a very tiny point in your image.

Where focus on a larger area or several points is required, such as with this landscape shot, ‘Multi-area Focus’ can be selected – so objects in the foreground, mid-ground and background are all sharp.

Landscape Multi POF F8

Objects in the foreground, mid-ground and background are in focus.


Depth of field

There will always be a distance in front of and behind the focus point that will also be in focus – this is called ‘depth of field’ (DoF). It is controlled by the aperture, the lens’ focal length and the distance between camera and subject.

This illustration shows how the DoF area in front of and behind the subject changes according to the aperture. The red zones show the areas in focus when different apertures are used to control DoF.

Depth of Field - Copy_edited-1

Shallow depth of field vs Deep depth of field

Bee F4 Spot Focus

A shallow Depth of Field draws the eye to the centre of this shot

A picture taken with a shallow DoF concentrates the eye on a shallow area, making the subject stand out from the background; you could say we are deliberately blurring the background for effect.

Using shallow DoF in this way works very well for portraits – as shown in the images above – and for close-up shots such as this pollinating bee (right). An f4 aperture was used, with the point of focus set on its eyes. Because the lens is so close to the subject, the DoF is just a few millimetres. The bee’s head and the flower’s stamen are in focus, but the front tips of the petals, the bee’s wings and the flower in the background are not.

When using a wide aperture to create a shallow DoF, the range of focus narrows the closer the camera gets to the subject. With macro shots like this, it is advisable to use a tripod – otherwise it is very hard to keep the point of focus exactly where you want it.


oulton-park-20-6-12-1000x750

Motion blur creates the effect of movement with the subject in focus, as in this panning shot of a racing car. Image taken by robin_ashby007.

Motion blur

We know detail can be seen when focus is good, but de-focus can also be useful. Motion blur – caused by movement of the subject, or of the camera – can also sometimes be intentional. As with focus blur, motion blur can be used creatively for emphasis. More specifically, the movement of a subject is emphasised, as in this panning shot of a racing car.

There is the effect of movement – our brains are tricked into ‘seeing’ it – even though the car is static in the frame. It was kept focused by panning the camera with it as it passed, using a shutter speed of 1/200th sec – not too fast, so as to keep the track blurred.

This type of shot requires a lot of practice! The panning speed of the camera must perfectly match the car’s motion – too fast or too slow, and the car would also be blurred.

Maclaren zoom

A longer exposure while zooming creates an interesting movement effect

The next image was slightly easier to achieve. It also gives a perception of speed, but actually the subject was static – an F1 car mounted on a display.

Taken at 1/6th sec and zooming out simultaneous to the shutter release, this slow exposure and movement of the lens creates the illusion of the car moving away from the viewer.


Manual Focus

Most shots can be taken using Auto Focus, but sometimes it is necessary to switch to manual.

Take for instance the shot of this house behind some trees. In this first shot, AF has fixed on the branches in the foreground – leaving the house itself blurred, but in the second shot you can see that turning AF off and focusing manually on the intended subject solves the problem.

Focus1

Auto Focus misses the intended subject

Focus2

Focused manually on the house

When looking at these two images, notice how you are automatically drawn to the point of focus, the branch in picture 1 and the house in picture 2. Always check what is in focus in your shot and make sure that it is the subject that you intended. Use manual focus if the camera’s AF struggles to capture the subject correctly (select MF on the focus mode control or in the menu under ‘Focus Mode’).

We look at full manual focus control, in detail, in our Advanced module.


The LUMIX Advantage

LUMIX G cameras include ‘Full Area Focusing’, meaning you can choose your focus point – any part of the touch-screen can be selected, even close to the edge or corners. Many other cameras can only select an area around the centre of the image.

Shooting Exercise

Try out the different AF modes on your camera – Multi-point, Single Point and, if it’s a LUMIX, Pin-point– on varied subjects. Notice how different parts of the scene are put into focus by the camera. Then try composing shots with objects in the frame that add interest – like the branches in our house shot – so you learn how to choose the correct focus mode. Experiment manually where AF lets you down!

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Written by Steve Lucas for Panasonic ©