Depth-of-Field and Video

One thing that makes digital still cameras so attractive for professional video shooters—especially now that cameras support 8K or 4K video—is that they have relatively large sensors, which provides improved low-light performance and results in the oddly attractive reduced depth-of-field, compared with many professional video cameras.

But wait! you say. No matter what size sensor is used, isn’t the number of pixels in that video frame exactly the same—1920 × 1080 pixels for, say, full HD? That’s true—the final resolution of the FHD video image is precisely 1920 × 1080 pixels, whether you’re capturing that frame with a smartphone, a professional video camera, the R7 with an APS-C sensor, or one of its full-frame counterparts like the EOS R6. But that’s only the final resolution. The number of pixels used to capture each video frame varies by sensor size.

For example, your camera does not use only its central 1920 × 1080 pixels to capture a full HD video frame. If it did that, you’d have to contend with a significant “crop” factor, and the field of view of a wide-angle lens would be sharply curtailed. Instead, it captures a full HD video frame using the full 22.3mm width of its APS-C sensor, trimmed to the proportions of a 16:9 area. Your wide-angle and telephoto lenses retain roughly their same fields of view as they do in still photography mode, and you can frame and compose your video through the viewfinder normally, with only the top and bottom of the frame cropped off to account for the wider video aspect ratio. That’s why your camera gives you such great video quality, and why your video images retain roughly the same field of view and exact same depth-of-field you get with full-frame still images in Full HD mode. As I noted in Chapter 16, you do have an optional 4K crop mode that extracts the video frame from the center of the sensor, with a 1.8X crop relative to the APS-C sensor.

Figure 17.2 shows at upper left the approximate capture areas for still photos, and video captured using the full width of a full-frame sensor like the one found in the EOS R6. Also shown in lower and right sides of the picture are the video capture areas for some professional video sensors, the wide-angle sensor in a typical iPhone, and the APS-C sensor found in the EOS R7. Keep in mind that many professional video cameras, like the EOS C70, now use APS-C-sized sensors, too.

The important thing to note is that a larger sensor calls for the use of longer focal lengths to produce the same field of view, so, in effect, a larger sensor has reduced depth-of-field. And that’s what makes cameras with APS-C or larger sensors attractive from a creative standpoint. Less depth-of-field means greater control over the range of what’s in focus. Your camera, with its larger sensor, has a distinct advantage over consumer camcorders in this regard, and even does a better job than many professional video cameras. With a really fast lens, such as the Canon RF 40mm f/1.2L USM, some sensational selective focus effects can be achieved.

Zooming and Video

When shooting still photos, a zoom is a zoom is a zoom. The key considerations for a zoom lens us ed only for still photography are the maximum aperture available at each focal length (“How fast is this lens?), the zoom range (“How far can I zoom in or out?”), and its sharpness at any given f/stop (“Do I lose sharpness when I shoot wide open?”).

When shooting video, the priorities may change, and there are two additional parameters to consider. The first two I listed, lens speed and zoom range, have roughly the same importance in both still and video photography. Zoom range gains a bit of importance in videography, because you can always/usually move closer to shoot a still photograph, but when you’re zooming during a shot most of us don’t have that option (or the funds to buy/rent a dolly to smoothly move the camera during capture). But, oddly enough, overall sharpness may have slightly less importance under certain conditions when shooting video. That’s because the image changes in some way many times per second (24/30/60 times per second in NTSC mode), so any given frame doesn’t hang around long enough for our eyes to pick out every single detail. You want a sharp image, of course, but your standards don’t need to be quite as high when shooting video.

Here are the remaining considerations:

◼  Zoom lens maximum aperture. The speed of the lens matters in several ways. A zoom with a relatively large maximum aperture lets you shoot in lower light levels, and a big f/stop allows you to minimize depth-of-field for selective focus. Keep in mind that the maximum aperture may change during zooming. A lens that offers an f/3.5 maximum aperture at its widest focal length may provide only f/5.6 worth of light at the telephoto position. If shooting wide open you may want to retain the same maximum aperture regardless of focal length, so depth-of-field (and, along with it, focus) will increase or decrease more predictably from shot to shot, because the focal length has changed (that is, going from wide-angle to tele, or the reverse), and not because the effective aperture has changed, too.

In that case, you’ll want to use a constant aperture lens (sometimes called a fixed aperture lens, which can be interpreted two ways). Often, such lenses are Canon L lenses; less expensive optics with a similar focal length range usually have a variable maximum aperture. A typical example is the RF 24-105mm f/4L. The L lens’s maximum aperture is f/4 from 24mm right up to 105mm.

◼  Zoom range. Use of zoom during actual capture should not be an everyday thing, unless you’re shooting a kung-fu movie. However, there are effective uses for a zoom shot, particularly if it’s a “long” one from extreme wide angle to extreme close-up (or vice versa). Most of the time, you’ll use the zoom range to adjust the perspective of the camera between shots, and a longer zoom range can mean less trotting back and forth to adjust the field of view. Zoom range also comes into play when you’re working with selective focus (longer focal lengths have less depth-of-field), or want to expand or compress the apparent distance between foreground and background subjects. A longer range gives you more flexibility.

◼  Linearity. Interchangeable lenses may have some drawbacks, as many photographers who have been using the video features of their digital cameras have discovered. That’s because, unless a lens is optimized for video shooting, zooming with a particular lens may not necessarily be linear. Rotating the zoom collar manually at a constant speed doesn’t always produce a smooth zoom. There may be “jumps” as the elements of the lens shift around during the zoom. Keep that in mind if you plan to zoom during a shot, and are using a lens that has proved, from experience, to provide a non-linear zoom. Lenses produced specifically for cine use have linear zooming— and also linear focus, important when doing “pull” focus effects, in which focus is changed from one plane to another during a shot.

Illumination

You can significantly improve the quality of your video by increasing the light falling in the scene. This is true indoors or out, by the way. While it may seem like sunlight is more than enough, it depends on how much contrast you’re dealing with. If your subject is in shadow (which can help them from squinting) or wearing a ball cap, a video light can help make them look a lot better.

Lighting choices for amateur videographers are a lot better these days than they were a decade or two ago. An inexpensive incandescent video light, which will easily fit in a camera bag, can be found for $15 or $20. You can even get a good-quality LED video light for less than $100. Work lights sold at many home improvement stores can also serve as video lights since you can set the camera’s white balance to correct for any color casts. You’ll need to mount these lights on a tripod or other support, or, perhaps, to a bracket that fastens to the tripod socket on the bottom of the camera.

Much of the challenge depends upon whether you’re just trying to add some fill-light on your subject versus trying to boost the light on an entire scene. A small video light will do just fine for the former. It won’t handle the latter. Fortunately, that versatility comes in quite handy here. Since the camera shoots video in Auto ISO mode, it can compensate for lower lighting levels and still produce a decent image. For best results, though, better lighting is necessary.

Creative Lighting

While ramping up the light intensity will produce better technical quality in your video, it won’t necessarily improve the artistic quality of it. Whether we’re outdoors or indoors, we’re used to seeing light come from above. Videographers need to consider how they position their lights to provide even illumination while up high enough to angle shadows down low and out of sight of the camera.

When considering lighting for video, there are several factors. One is the quality of the light. It can either be hard (direct) light or soft (diffused) light. Hard light is good for showing detail, but can also be very harsh and unforgiving. “Softening” the light, but diffusing it somehow, can reduce the intensity of the light but make for a kinder, gentler light as well.

While mixing light sources isn’t always a good idea, one approach is to combine window light with supplemental lighting. Position your subject with the window to one side and bring in either a supplemental light or a reflector to the other side for reasonably even lighting.

Lighting Styles

Some lighting styles are more heavily used than others. Some forms are used for special effects, while others are designed to be invisible. At its most basic, lighting just illuminates the scene, but when used properly it can also create drama. Let’s look at some types of lighting styles:

◼  Three-point lighting. This is a basic lighting setup for one person. A main light illuminates the strong side of a person’s face, while a fill light lights up the other side. A third light is then positioned above and behind the subject to light the back of the head and shoulders. (See Figure 17.7, left.)

◼  Flat lighting. Use this type of lighting to provide illumination and nothing more. It calls for a variety of lights and diffusers set to raise the light level in a space enough for good video reproduction, but not to create a mood or emphasize a scene or individual. With flat lighting, you’re trying to create even lighting levels throughout the video space and minimize any shadows. Generally, the lights are placed up high and angled downward (or possibly pointed straight up to bounce off a white ceiling). (See Figure 17.7, right.)

◼  “Ghoul lighting.” This is the style of lighting used for old horror movies. The idea is to position the light down low, pointed upward. It’s such an unnatural style of lighting that it makes its targets seem weird and “ghoulish.”

◼  Outdoor lighting. While shooting outdoors may seem easier because the sun provides more light, it also presents its own problems. As a general rule of thumb, keep the sun behind you when you’re shooting video outdoors, except when shooting faces (anything from a medium shot and closer) since the viewer won’t want to see a squinting subject. When shooting another human this way, put the sun behind her and use a video light to balance light levels between the foreground and background. If the sun is simply too bright, position the subject in the shade and use the video light for your main illumination. Using reflectors (white board panels or aluminum foil–covered cardboard panels are cheap options) can also help balance light effectively.

Tips for Better Audio

Since recording high-quality audio is such a challenge, it’s a good idea to do everything possible to maximize recording quality. Here are some ideas for improving the quality of the audio your camera records:

◼  Get the camera and its microphone close to the speaker. The farther the microphone is from the audio source, the less effective it will be in picking up that sound. While having to position the camera and its built-in microphone closer to the subject affects your lens choices and lens perspective options, it will make the most of your audio source. Of course, if you’re using a very wide-angle lens, getting too close to your subject can have unflattering results, so don’t take this advice too far. It’s important to think carefully about what sounds you want to capture. If you’re shooting video of an acoustic combo that’s not using a PA system, you’ll want the microphone close to them, but not so close that, say, only the lead singer or instrumentalist is picked up, while the players at either side fade off into the background.

◼  Use an external microphone. You’ll recall the description of the camera’s external microphone port in Chapter 2. As noted, this port accepts a stereo mini-plug from a standard external microphone, allowing you to achieve considerably higher audio quality for your movies than is possible with the camera’s built-in microphones (which are disabled when an external mic is plugged in). An external microphone reduces the amount of camera-induced noise that is picked up and recorded on your audio track. (The action of the lens as it focuses can be audible when the built-in microphones are active.)

The external microphone port can provide plug-in power for microphones that can take their power from this sort of outlet rather than from a battery in the microphone. Canon provides optional compatible microphones such as the Canon Directional Microphone DM-E1D (around $300, see Figure 17.8). When plugged into the R7’s multi-function shoe, no external cable is required; it draws power from and directs audio signals to the camera through contacts in the shoe itself. You also may find suitable microphones from companies such as Shure and Audio-Technica. If you are on a quest for superior audio quality, you can even obtain a portable mixer that can plug into this jack. Or, you might be using an Atomos recorder with professional microphone jacks. One good thing about Canon still cameras is that so many pro videographers are using them that a wealth of add-on video gear, from monitors to cages and stabilizers, is available for them.

◼  Hide the microphone. Combine the first few tips by using an external mic, and getting it as close to your subject as possible. If you’re capturing a single person, you can always use a lapel microphone (described in the next section). But if you want a single mic to capture sound from multiple sources, your best bet may be to hide it somewhere in the shot. Put it behind a vase, using duct tape to fasten the microphone, and fix the mic cable out of sight (if you’re not using a wireless microphone).

◼  Turn off any sound makers you can. Little things like fans and air handling units aren’t obvious to the human ear, but will be picked up by the microphone. Turn off any machinery or devices that you can plus make sure cell phones are set to silent mode. Also, do what you can to minimize sounds such as wind, radio, television, or people talking in the background.

◼  Make sure to record some “natural” sound. If you’re shooting video at an event of some kind, make sure you get some background sound that you can add to your audio as desired in postproduction.

◼  Consider recording audio separately. Lip-syncing is probably beyond most of the people you’re going to be shooting, but there’s nothing that says you can’t record narration separately and add it later. It’s relatively easy if you learn how to use simple software video-editing programs like iMovie (for the Macintosh) or Windows Movie Maker (for Windows PCs). Any time the speaker is off-camera, you can work with separately recorded narration rather than recording the speaker on-camera. This can produce much cleaner sound.

External Microphones

The single most important thing you can do to improve your audio quality is to use an external microphone. The camera’s internal stereo microphones mounted on the front of the camera will do a decent job, but have some significant drawbacks, partially spelled out in the previous section:

◼  Camera noise. There are plenty of noise sources emanating from the camera, including your own breathing and rustling around as the camera shifts in your hand. Manual zooming is bound to affect your sound, and your fingers will fall directly in front of the built-in mics as you change focal lengths. An external microphone isolates the sound recording from camera noise.

◼  Distance. Anytime your camera is located more than 6 to 8 feet from your subjects or sound source, the audio will suffer. An external unit allows you to place the mic right next to your subject.

◼  Improved quality. Obviously, Canon wasn’t able to install a super-expensive, super-high-quality microphone, even on an advanced camera. Not all owners of the camera would be willing to pay the premium, especially if they didn’t plan to shoot much video themselves. An external microphone will almost always be of better quality.

◼  Directionality. The camera’s internal microphone generally records only sounds directly in front of it. An external microphone can be either of the directional type or omnidirectional, depending on whether you want to “shotgun” your sound or record more ambient sound.

You can choose from several different types of microphones, each of which has its own advantages and disadvantages. If you’re serious about movie making with your camera, you might want to own more than one. Common configurations include:

◼  Shotgun microphones. These can be mounted directly on your camera, although, if the mic uses an accessory shoe mount, you’ll need the optional adapter to convert the camera’s shoe to a standard hot shoe. I prefer to use a bracket, which further isolates the microphone from any camera noise. One thing to keep in mind is that while the shotgun mic will generally ignore any sound coming from behind it, it will pick up any sound it is pointed at, even behind your subject. You may be capturing video and audio of someone you’re interviewing in a restaurant, and not realize you’re picking up the lunchtime conversation of the diners seated in the table behind your subject. Outdoors, you may record your speaker, as well as the traffic on a busy street or freeway in the background.

◼  Lapel microphones. Also called lavalieres, these microphones attach to the subject’s clothing and pick up their voice with the best quality. You’ll need a long enough cord or a wireless mic (described later). These are especially good for video interviews, so whether you’re producing a documentary or grilling relatives for a family history, you’ll want one of these.

◼  Hand-held microphones. If you’re capturing a singer crooning a tune, or want your subject to mimic famed faux newscaster Wally Ballou, a hand-held mic may be your best choice. They serve much the same purpose as a lapel microphone, and they’re more intrusive—but that may be the point. A hand-held microphone can make a great prop for your fake newscast! The speaker can talk right into the microphone, point it at another person, or use it to record ambient sound. If your narrator is not going to appear on-camera, one of these can be an inexpensive way to improve sound.

◼  Wired and wireless external microphones. This option is the most expensive, but you get a receiver and a transmitter (both battery-powered, so you’ll need to make sure you have enough batteries). The transmitter is connected to the microphone, and the receiver is connected to your camera. In addition to being less klutzy and enabling you to avoid having wires on view in your scene, wireless mics let you record sounds that are physically located some distance from your camera. Of course, you need to keep in mind the range of your device, and be aware of possible signal interference from other electronic components in the vicinity.