Take control of depth of field
Controlling depth of field is the key to successful photography. Managing what is in focus (and out of focus) is strongly linked to the enjoyment of the image and this varies greatly with relation to subject matter. Landscape photography, for example, uses a large depth of field, keeping the entire image in sharp focus from corner to corner. This invites the eye to explore fine detail and truly experience distances, from distant cloud shapes to the wet sand at your feet.
Macro photography, on the other hand, places these sharp areas alongside large out-of-focus areas (find out How to set your autofocus for macro photography). A fine stamen set against a riot of soft blurred shapes renders a flower delicate and the experience becomes more intimate.
The next time you look at some compelling advertising, identify what the advert is trying to sell and the photographic technique used to reflect this.
Whether it’s jewellery or a package holiday, the depth of field will keep your eye exactly where it should be – on the product. So how can you improve your use of depth of field?
Understanding your lenses intimately is the best answer (check out The Canon lens companion for more on how to use your lenses).
Depth of field increases either side of the focal plane (or focal point) as the aperture is increased, bringing areas either side of this sharpness into focus. A wide aperture (such as f/2.8) will contain very little of the image in focus whereas a large aperture (such as f/16) will render much more of the image sharp (download a free f-stop chart for understanding aperture).
This is again subject- and lens-dependant. There is no reason to shoot a distant landscape with a telephoto lens at f/16 because it doesn’t contain anything close to the photographer.
A wider aperture will suffice. Telephoto lenses exhibit a far reduced depth of field at f/16 than a wide-angle lens, so understanding just how much your lens can render is vital to an image’s success.
Focus your lenses
Learning to focus your lenses hyperfocally is the answer to many landscape headaches (see a quick guide to What is hyperfocal distance? Or you can drag and drop download our free hyperfocal distance calculator chart on this page).
Imagine a mountain scene containing a house and some garden flowers around a metre away. It is possible to shoot all this in focus if the focusing is positioned correctly to use the areas in front of and behind the focal point.
With the lens focused on the mountain (at infinity) the flowers in the foreground can’t seem to get focus, even at f/22. This is because the area behind the focal plane is not being used. By moving the focal point back towards the house, the lens now uses the area both in front and behind, which means the flowers snap into focus without losing sharpness throughout the image.
Essential camera tips for controlling depth of field
Take manual control
When setting depth of field, set the camera to Av or M (Aperture Priority or Manual) to make sure you have complete control over your composition and the areas that appear in focus. Keep your lens switched to manual focus (MF), too.
Use Depth of Field Preview
Your camera’s Depth of Field Preview function is vital for assessing depth of field, before you press the shutter. Remember, until this button is depressed, the lens will only show the image at the widest aperture.
Switch to Live View
Live View (available on most modern D-SLRs) is your best friend. Press the Depth of Field Preview button while in Live View mode and you will be able to see exactly what’s in focus. This helps you position the focal point to maximise the in-focus area.
Depth of field and macro photography
Choosing the right aperture to shoot at for flower portraits can be tricky. Here’s how to get it right (click to enlarge the image below)
Flower portraits can respond well to varying depths of field, but identifying the right aperture can be tricky. Shooting this military orchid at a narrow depth of field creates a greater sense of dimension and also blurs the background out to a smooth green.
The f/16 shot, on the other hand, looks much more like a ‘record shot’, because the flower is entirely sharp. Basically, the aperture you choose depends on the effect you want to achieve. The joy of digital is that you can experiment on location until you get the result you want.
Final tips for controlling depth of field
Use a tripod
Image accuracy will make or break the shot, so ensure you have a steady tripod to mount your camera on. Vibration can also cause problems with softness, so ensure that all the locks and knobs are tightened up before shooting (see our 4 tips for sharper shots when using a tripod).
Speed things up
Wide apertures can let you break free of the tripod and shoot handheld instead, as a narrow depth of field (f/2.8, for instance) means faster shutter speeds. Vary the ISO to give even greater control and respect the 1/focal length rule (shooting with a 50mm lens at no slower than 1/50 sec).
Check your focus
Disable autofocus or engage it respectively, depending on your subject matter and picture style. Remember to check your focusing regularly when shooting landscapes using manual focus. Mistaking the focus ring for the zoom can ruin all your shots.
Bracket your focusing
Try moving the focusing either side of the assumed focal plane when you’re shooting at greater depth of field. Take a few initial shots, then shoot a few extra exposures at different focal points as a safeguard against focus error.
This entry was posted on Wednesday, May 9th, 2012 at 12:15 pm and is filed under Canon D-SLR Skills, Photography Tutorials. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a comment. Pinging is currently not allowed.