Manual Modes
In the middle to higher-end cameras, you’ll begin to see options for manual modes like Av, Tv, and M; you may also see some labeled P and A-DEP. I’ll start with what I think are the three most common ones listed at the beginning.
Av Mode
Av is the symbol for aperture priority mode, where aperture is the term for an opening that allows light to pass. The “smaller” an aperture is, the less light it can let through, and counterintuitive though it may seem, the higher the number it has. An aperture in our camera really has only that one function, but that function changes a picture dramatically from end to end.
On the left, f/1.8, and on the right, f/22; note the difference in the background
Light hitting your camera comes from nearly the full half-hemisphere of available light that exists parallel to and in front of your lens. Generally, the light from your subject is coming almost directly towards you; background and surroundings will send light in from both narrow and wider angles. Your aperture, as it gets smaller, will make the cone of light that can get through to your sensor smaller, meaning that off-angle light from both background and surrounding light gets removed from the image. With the off-angle rays removed, more of the background becomes focused. This is where the major difference between wide-open and more closed apertures becomes clear: a wide-open (lower-value) aperture will make your background blurry and unfocused. Depending on the lens construction, it can look fantastic or somewhat less pleasing. Bokeh, as it’s called, is a name describing the characteristic blur of a particular lens at wide aperture settings. For instance, you can refer to a particular lens having a “nice bokeh” if you find its blur style pleasant.
Bokeh nicely sets off the crisp text from the background
Bokeh is rumored to have sprung from the Japanese boke, which can be translated as “fuzzy,” and should give you an idea how to pronounce it. Bokeh can thus be used to provide separation between subject and background, or to disguise or remove an otherwise unpleasant background; this is manipulating the “focus plane.” A focus plane is just what it sounds like, a region of space that is in focus. With a wide aperture, there’s only a thin focus plane since all of those off-angle rays are being captured. With a smaller aperture, more focused rays are collected and the focus plane deepens, allowing a more focused background. With a wide enough aperture, the focus plane may be sufficiently thin to prevent you from capturing the whole subject in full focus, as is often the case with macro shots.
This macro shot has such a thin depth of field that the whole frog can’t even be captured in focus
Apertures are denoted in f-stops, such as f/1.4, f/3.5, or even a range, as in f/3.5-5.6. An f-stop is actually the ratio of focal length to entrance pupil diameter, and to make it just a tiny bit more confusing, it’s not a linear rate. An f/4 lens doesn’t gather twice as much light as an f/8 lens, it actually gathers 4 times as much. In practice, wherever you see an f number, that will indicate the minimum aperture of the lens, or the widest it can open. Almost all lenses nowadays extend to f/22 from wherever they start. Lenses with only one focal length, or “primes,” will only have one f number. Zoom lenses, if extremely well-constructed, may also have only one f number. More often than not, however, you’ll run into a ranged f number like I listed above, where the smaller number is the widest aperture available to you when the lens is fully retracted (zoomed all the way out) and the larger number is the widest available when the lens is fully zoomed. The difference arises because of the higher amount of glass the light has to pass through in a zoom lens and the fact that its focal length changes as you zoom.
So I’ve told you all about what aperture is and how it can affect your shots, but I’m still not done. Don’t fret, now we get to the easy part – the mode definition. Av priority mode is simply the mode in which you can force your camera to use a specific aperture. While that seems anticlimactic, it’s a very useful mode, and the one I personally spend most of my shooting time in. If I want to shoot in low light or separate the background from a subject, I can go to Av mode and select my lowest aperture that will let me do so. If I’m shooting a group photo or a bright landscape, however, I might switch up to a higher aperture like f/8 or f/11 to try and catch more in my focus plane. If you’ve stuck with me this long, you’re practically home free. There are no tricky technical sections left; aperture is by far the most complex part of your camera, in my opinion. That said, let’s move on to Tv priority mode.
Tv Mode
Tv priority mode is your shutter speed mode. This will allow you to govern exactly how long the sensor’s left exposing after you press the shutter button, and will be shown in your camera ranging from thousandths of a second to 30 seconds or longer. Shutter speed determinations are usually centered around motion – either stopping all of it, allowing good motion, or eliminating bad motion. For handheld shots, as an example, the general rule of thumb is to set the shutter speed to 1/60 or shorter (that’s one sixtieth of a second). This is a small enough window that you’re likely to avoid capturing the movement that you inevitably introduce by holding your camera as opposed to putting it on a tripod or setting it down somewhere. If you’re zoomed in, however, you may have to shorten it even further than that; the longer the zoom, the more even the tiniest movements get magnified in the end image. On the other hand, if you’re trying to capture an action shot at a sporting event, or freeze the flow of a waterfall in time, you’ll want to raise the shutter speed fast enough that the sensor can’t even tell anything was ever moving in the image to begin with.
A long exposure captures ball travel on the left, while a short one captures individual water droplets on the right
Pump the speed up to 1/1000th or 1/2000th and you’re likely to freeze most action you’ll see on a daily basis. If you’d like, on the other hand, to see some motion blur and capture the flow of a waterfall or a car passing by, you’ll want to lengthen your shutter speed. This is, however, likely going to necessitate the use of a tripod or other method to stabilize the camera while the shutter’s open. Long shutter speeds are also magnificent for night shots; you can leave it open for an extended time to allow the camera to really pull in all the colors and objects that you wouldn’t have time to capture otherwise. Values you’ll see on camera spec sheets will usually be the full range of speeds, represented something like 1/4000 – 30 sec. My Canon 30D has shutter speeds ranging from a blisteringly fast 1/8000th of a second to a timed 30-second shutter, as well as what’s called a bulb mode, where the shutter stays open as long as I hold the shutter button down.
Bulb mode in action
Bulb mode is fantastic for night shots and particularly fireworks; hold the shutter down before they go up, wait for the explosion, then release. You don’t have to worry about focusing time or a late reaction, and since the shot is brightly-colored fireworks against a dark sky, you’re usually not taking in any light you don’t want to.
M Mode
If you’ve read through Av and Tv modes, you’ll notice that all that had to be done in those modes was to set one value – the aperture or the shutter speed. For that reason, those are considered semi-automatic modes: ones where you have control over more advanced settings, but once you’ve picked your options, the camera will figure everything else out for you. For example, if I pick an f/1.4 aperture on a ridiculously bright day, the camera will automatically shorten my shutter speed so as to prevent me from getting an entirely white picture. Same thing for the shutter speed priority mode, as it will select an aperture that will allow enough light in based on the speed I’ve selected so I don’t end up with an entirely black image. M mode, then, is the full Manual mode. You get to set aperture and priority at the same time and have full control over everything.
Manual controls come in handy for time-lapses like these
This is where the fact that it’s digital photography comes in wonderfully handy. If you screw up, you know it right away, because the review option will show you your image right after you’ve taken it on the handy screen they’ve got right there on the camera! In the days of film, this was impossible. You took your shot, went home, developed your roll, and if you were still learning, prayed that it was good. Otherwise, you were back out with another roll of film hoping for the same exact lighting conditions so you could try again. Instant feedback is heavenly. You select M mode, then fiddle with your dials or sliders until you get to the aperture and speed you want, punch your shutter, review, and retry if necessary. It’s an incredibly fun way to get to explore exactly how your optics work and experiment with different types of exposures.
A-DEP and P modes
A-DEP and P modes are more specific to higher-end cameras, so I’ll talk briefly about them together here. A-DEP is the automatic depth-of-field mode, and this goes back a little bit to the aperture discussion. As you remember, a wider aperture results in a smaller focus plane depth, or depth of field. If you’re taking a group photo or a landscape shot, however, you want everything to be in focus. If you feel like playing around in Av mode, you can use a depth of field preview button (if your camera has one) to force the lens into the currently-selected aperture setting in order to see if everything’s in focus. If your camera has an A-DEP mode, however, you can enter that and let the camera do some of the work for you. With my 30D, the A-DEP mode takes all 9 autofocus points and attempts to see if there’s anything worth focusing on; it then adjusts the aperture to achieve the depth of field necessary to focus on everything it found in the image.
Plenty for A-DEP to focus on here
P mode, or program mode, is essentially like the automatic mode mentioned at the beginning. The difference here is that some extra functions are enabled, but shutter speed and aperture are still handled by the camera. This mode is useful if you just need access to some features like burst-fire (how quickly your camera should take another picture once the current one fires) or ISO speed (a sensitivity setting we’ll go into later). If your camera has a P mode, check out the manual to find out what the differences are between the automatic and program modes, as there are far more settings than we have time to go into here.
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