Canon photography tips for depth of field and focusing
20 Aperture Priority
The three main factors that control depth of field (DoF) are your choice of aperture, focal length and focusing distance. The best way to set the aperture is to use the semi-auto Av (Aperture value) mode: you dial in the aperture (for your chosen lens), and your camera sets the appropriate shutter speed to produce a standard exposure. Set a wide aperture of f/4 for shallow DoF, and narrow aperture of around f/16 for maximum DoF.
21 Focal length
As FOCAL length increases (lengthens), the depth of field decreases, and vice versa. So a wide-angle lens (anything wider than 35mm, essentially) will naturally capture more depth of field. This means that when they're used at a narrow aperture, they can render whole landscapes sharp, from the foreground to the horizon.
In contrast, longer focal lengths capture a progressively shallower depth of field. Telephoto lenses (70mm and above) are better for portraits, as when combined with a wide aperture they really blur backgrounds.
22 Focusing distance
by focusing on subjects or objects very close to you, you reduce depth of field, leaving the scene behind your focal point blurred (even when you're using narrow apertures). Whereas, by focusing on distant objects or subjects, you will increase depth of field.
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23 What's the best aperture?
THE widest or narrowest aperture available on your lens isn't always the best choice. Here, the widest aperture of f/4 has knocked the background well out of focus, but only a small part of the flower is sharp. The narrowest aperture of f/22 has brought the entire flower into focus, but also rendered the background so it becomes a distraction. While an aperture of f/8 gives the best of both. A mid-range aperture will also capture optimum image quality, too.
24 Pin-point focusing
When capturing scenic shots, use your DSLR's Live View and LCD to focus with the upmost accuracy. First set a narrow aperture of around f/16, then set the lens to MF and manually focus on what's most important in your scene (the tree in our example), zooming in to x5 and x10 view to check the sharpness.
25 Shake-free shots
Don't fire a tripod-mounted DSLR by pressing the shutter release. Switch to a remote control (or use your camera's self timer) to ensure sharp photos.
26 Hybrid sensor
The hybrid CMOS sensor on the newest EOS DSLRs, such as the 750D and 760D, offers improved AF performance in Live View when using the LCD touchscreen.
27 Central AF point
For moving subjects or backlit subjects (when there's little contrast for the autofocus to latch on to) use the centre AF point, as it's the most sensitive.
28 Less DoF with full-frame
Using the same lens, aperture and focusing distance as an APS-C camera, a full-frame Canon DSLR will naturally capture a shallower DoF.
29 Mirror lockup
Even if you use a tripod and self-timer, the action of the mirror being raised can cause camera shake. Activate the camera's Mirror lockup setting to prevent this.
Canon photography tips for shutter speed and sensitivity
30 Be prepared to wait
Long Exposure Noise Reduction doubles the length of time it takes to produce every long exposure image because it creates a 'dark frame' for each shot.
31 When to use a tripod
If the shutter speed drops below the equivalent focal length of your lens - such as 1/100 sec for a 100mm lens on a full-frame EOS camera - then use a tripod.
32 ISO Expansion
In dark conditions, expand the sensitivity range of your camera via the Custom Functions menu, although the top values (H1 and H2 etc) do give noisy results.
33 Flash sync in Av mode
In Aperture Priority the camera sets the shutter speed. If you're using flash it can be helpful to set the sync speed via the Custom menu to prevent long exposures.
34 Sharp and blurred
Mix a long exposure with flash (in Second-curtain sync mode) when shooting a moving subject to get soft, blurred movement trailing behind a sharp subject.
35 'Time value' mode
Tv on the Mode dial of Canon cameras stands for Time value mode, but it's more commonly known as Shutter Priority mode. It's a great semi-automatic option that allows you to set the shutter speed while the camera takes care of the aperture.
This means it's really useful when you want to control how the subject's movement is captured: frozen or blurred. It also lets you dial in a 'safe' shutter speed for sharp photos when you're using the camera handheld, rather than on a tripod.
36 Ultra-long exposures
A long exposure can lift a mundane scene by recording moving elements as a blur. Even at low ISOs and with narrow apertures, normal daylight conditions don't permit long exposures, but exposure time can be extended by using a strong neutral density filter, such as Lee Filters' Big Stopper. This 10-stop ND extends shutter speeds by 960x, turning an exposure of 1/60 sec into one that stretches for 15 seconds.
37 ISO control
High sensitivity settings are useful when you need to shoot moving subjects or handhold the camera in low light because they allow you to use fast shutter speeds. As a rule, though, it's a good idea to keep within the 'native' ISO range and only use the expansion settings in an emergency. When the camera's mounted on a tripod and the subject isn't moving, use the lowest native sensitivity setting (ISO100) to minimize noise.
38 Moving subjects in low light
A fast shutter speed is essential to freeze movement, so if you're shooting a moving subject in low light there's no alternative but to use a wide aperture and/or high ISO. If you set the camera to Tv and Auto ISO, it'll adjust the aperture and sensitivity while you take care of the shutter speed. Once you've found a value that freezes the subject, stick with it and adjust the brightness using exposure compensation.
39 Auto sensitivity
Using Auto ISO in combination with Manual mode gives you all the power of Manual mode with zero hassle. It's a sort of Aperture and Shutter Priority in one, as you can set the combination of aperture and shutter speed you want, then just leave the camera to work out the correct ISO.
Helpfully, several Canon DSLRs, including the 70D and 700D, allow you to set the maximum ISO value for Auto ISO, stopping the camera from using the noisy upper values. Some even let you specify a minimum shutter speed as well, so you can prevent blurred shots.
Canon photography tips for mastering manual mode
Use the histogram as a guide to your manual exposures, in the same way as you would for other shooting modes and avoid 'clipping' its right-hand edge.
41 Set up your dials
By default your DSLR's control dials change exposure by 1/3 of a stop for each dial click. If you prefer, you can set this to 1/2 stop in the Custom Functions.
42 Floating apertures
Many zooms have a narrower aperture at the long end than they do at the short end, so you'll need to remember to adjust the shutter speed or ISO to compensate.
43 Manual mode for video
When shooting video, a good stock Manual mode setting is to set a shutter speed of 1/50 sec then use the lowest possible ISO your chosen aperture will allow.
44 Make test shots
Manual Mode used to be more tricky in the days of film, but these days, you can take a test shot and then adjust the exposure accordingly. Too bright? Simply increase the f-number, shorten the shutter speed or lower the ISO. Too dark? Then either lower the f-number, lengthen the shutter speed or up the ISO.
By balancing the combination of shutter speed, aperture and ISO, you also have an extra degree of control over the depth of field, exposure length and image quality.
45 In the studio
Manual Mode is the ideal choice any time you're photographing a subject under controlled lighting conditions, such as in a studio. Set ISO to 100 and dial in a shutter speed of 1/200 sec, then control your exposure using aperture and flash power.
46 Take control of metering
Your DSLR's metering system isn't as clever as you! Only you know which parts of a scene you want to be correctly exposed. For example, you might want a dramatic silhouette, while your metering system may instead expose for the subject. Many photographers use spot or partial metering in Manual mode, as this enables you to take a reading from a specific area of the scene.
47 Exposure Compensation
You can't dial in Exposure Compensation in Manual mode in the same way as in the Av and Tv modes. However, you can still use the exposure indicator, visible in your viewfinder and top plate display, as a guide. As you have full control over aperture and shutter speed, it's up to you which you adjust to brighten or darken your exposures; the indicator will move along the scale as you make changes.
48 Bright or dark?
The position of the indicator on the exposure scale depends on the area being metered by the camera. As a rule of thumb, adjust your settings so that when you meter a midtone, such as grass or a pavement, the indicator is in the middle of the scale. If you point it at a brighter area, then it will move towards the '+' end, and then move towards the '-' end when it's pointed towards a darker area, but your midtone exposure will stay locked in.
49 Auto Exposure Bracketing
Bracketing means taking a series of frames close to what your camera considers to be the 'correct' exposure, just in case it's wrong. You can set up Auto Exposure Bracketing in your camera's red Shooting menu - look for 'Exposure comp/AEB setting' - or by selecting it on the Quick Control screen.
The AEB function enables you to choose the exposure difference between the shots. If you need to fire the three frames quickly, set the camera's Drive mode to High-speed Continuous. Once you've got a set of exposures, you can choose the one that looks right, or even blend several using HDR software.
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