Making movies
someone being interviewed. With a middling aperture giving a relatively large depth-of-field, using manual focus is an easy and safe option. However, when things are moving or you want to do focus pulls, it’s a bit trickier. Big-budget dramas and films employ a focus puller, who has a wireless monitor linked to the camera to see what the camera sees, and a wireless controller unit linked to a focus motor mounted on the lens. This trained expert constantly tweaks the lens using the controllers to focus on exactly what the director wants. Focus pulls, tracking moving people and objects – it’s all done manually. For one-person shooting, of course this isn’t possible. The first issue is seeing when the image is actually sharp. For this, “For many subjects, a slow speed of focus and a sticky transition is a good move”
contrast detection and on-sensor phase detection to stop the hunting, which works well in many cases. But any AF system can make mistakes. Many hybrid systems allow you to set the AF area to a ‘wide’ mode where the camera constantly tries to work out what the main subject is. This can work well in general scenes at middle apertures, but you have to be prepared for the odd mistake. If two people enter the frame, for example, the camera won’t know who the main subject is so might make a guess – and get it wrong. Some cameras will allow you to tap the touchscreen to identify the main subject. Often, you can set a certain part of the frame to be the main focus area. This can be a third of the frame, or a tiny box that you can move around with the joystick. Of course, none of this helps that much if your subject suddenly moves out of that area. If your camera has specific subjects it can recognise and focus on – such as cars, boats, trains, animals, birds or even humans – then this can help.
And face detection or eye detection can be a godsend, especially when using fast lenses wide open for a shallow depth-of-field. But again, this isn’t always 100% accurate every time. Most cameras also allow you to set the focus speed and the transition speed or ‘stickiness’ – that is, to what degree it will stay with a subject before looking for something else to focus on. For example, if you’re shooting a person walking towards you in the park and a dog runs across the scene, you don’t want the AF to snap onto the dog then back to the person when the hound has left the frame. So for many subjects, a slow speed of focus and a sticky transition is a good move. However, if you are shooting racing cars or runners, you will want a faster AF speed. For video, there is no one-size-fits-all setting. You have to experiment and see what works for your scene. Many video shooters who rely on AF are constantly changing settings for different shots. The ‘old-school’ option Many filmmakers have used manual focus for years and won’t use anything else. Of course, this is easy when you are locked down on a tripod and shooting things that don’t move, like a general landscape view or even
can really work well if you are serious about manual focusing. The tactile, direct response of cinema lenses isn’t the only benefit. They often have a faster maximum aperture that’s measured in T stops, which are more accurate than f/stops. And they have click-less aperture rings so exposure changes can be smoother. But one of the biggest benefits is their lack of focus breathing. In photo lenses, when going from minimum focus to infinity, the actual angle of view and magnification of the lens changes. For shooting stills, you don’t really notice it too much unless you’re focus stacking. But when you shoot a video and do a focus pull, it can be obvious and disconcerting. An all-manual cinema lens is made to reduce this as much as possible. This is true for primes as well as zooms. While most cine lenses are primes, there are some cinema zooms too. These are designed to be parfocal, which means their point of focus stays perfectly consistent throughout the entire range of the lens’ zoom. Some stills zoom lenses are parfocal, but many very clearly aren’t – which can be quite the problem when shooting video. These are called varifocal lenses and should be avoided for moviemaking if possible. The best setting? There is no single setting that’s a magic formula for video. Sometimes, manual focus is best. Other times, you might want speedy AF for tracking a fast-moving subject. And in some instances, a slow-speed AF to give a more natural feeling for slow-moving subjects or for doing focus pulls. So experiment – and have fun. PN
cameras often have a focus-peaking setting where a brightly coloured outline appears on the edge of subjects that are sharp. The colour can often be changed to aid viewing, and it’s a very useful tool for manual focusing, even if you are using the camera’s own screen as a monitor. For serious work, it’s best to invest in an external monitor that uses a screen of five inches or above. This makes it much easier to see the image, and most monitors also have their own focus-peaking settings. When it comes to using an AF lens in manual-focus mode, they use a ‘fly-by-wire’ system instead of a direct, mechanical system as found in old- school manual lenses. Some cameras let you adjust the focus response and speed, to give it a more linear feel. Even so, these lenses aren’t ideal for manual focusing for video, but they can work. Benefits of cine glass Real cinema lenses are designed for manual focusing. They have a very long throw, making them far more accurate. You can just turn the focus ring by hand, but they are designed to be used with a follow-focus attachment on their geared control wheels. You can use a follow-focus on an AF lens, but usually need to buy rings that stretch over the focus ring to allow it to match the teeth of the follow-focus device. These often bolt to a camera cage or bottom plate that has 15mm rails. Of course, this adds weight, bulk and expense, but THE OLD WAYS ARE BEST Different AF settings suit different shots – but sometimes manual is the only option
STEADY AS SHE GOES Cinema zoom lenses are parfocal, which means they retain their focus when zoom is adjusted
Issue 107 | Photography News 29
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