dSLR tips for beginners: How to use Manual mode

What it is

While in anything other than full auto mode you can control all a camera's settings, but only Manual mode lets you adjust aperture and shutter speed independently.

For more information about other cameras modes, check out what all those camera modes are for, anyway.

Who can use it

Manual mode is for anybody with a mode dial on their camera, physical or virtual, dSLR, interchangeable-lens mirrorless, advanced compact or even a phone with manual controls. Note that on low-end cameras there might be a manual option, but it's not always really Manual -- it's just a less-automatic mode.

Using Manual mode is tons easier with a digital camera than it previously was with film, because you can see immediately if the settings aren't working. Even with modern film cameras, the light meter in the viewfinder would indicate if the exposure was "correct," but usually you had to rely on rules of thumb like Sunny 16 to figure out where to start. Now, if you have no clue what settings to start with, you can stick it in Program mode or Shutter-priority mode and see what the camera chooses, then switch to Manual and adjust from there.

However, to use Manual you still need to have a basic grasp of the relationships between ISO speed, shutter speed and aperture value. If you don't understand them -- or don't understand the way I describe it -- persevere by reading lots of different descriptions. Everyone learns differently, and sometimes it takes just the right explanation before you have that "Aha!" moment. Some folks understand better by looking at the math, some by diagrams, some by graphs, and some just by looking at and taking photos.

When to use it

As a Twitter commenter put it: "Real photographers use Manual mode, that way you tell the camera what you want, no surprises with automation." This echoes a common sentiment. While I disagree with the "real photographers" comment -- real photographers use whatever tools they have to get the job done and aren't afraid to be seen using some automation when it's more efficient -- he is more or less right about the "no surprises" part. The thing is, before you've mastered manual mode, it's pretty much all surprises -- both good and bad. So when you're starting out, don't use it in situations where a missed photo will be a problem.

In the beginning, the best times to start out with Manual mode are:

• When you photograph the same thing under the same conditions, over and over again. For instance, when I first started shooting a particular night scene for camera testing, I'd repeatedly try spot metering off different places to get the exposure I wanted in Shutter-priority mode (with fixed ISO sensitivity, since that's what I'm testing). Then came my "D'oh!" moment, and I switched to manual, since I'd already figured out the settings I needed. Since each camera's a little different, I still have to tweak the settings, but it's still much faster.
• When you're photographing under unchanging lighting. Why make the camera recalculate the exposure with every shot? And even though the lighting isn't changing, chances are the camera will still deliver different exposure choices for similar shots if you're using some form of auto.
• When the lighting is changing radically. Setting your shutter speed and aperture and allowing Auto ISO sensitivity to float the setting ensures your shutter speed and aperture will stay in the safe zones. Normally I don't recommend Auto ISO, but in very dark conditions you're going to end up with a high sensitivity anyway, so you might as well just end up with it automatically.
• When the metering system delivers unexpected exposures. How many times has your camera produced an under- or overexposed shot based on its metering decisions, and you just keep retaking and retaking, hoping the next will be different? It's the definition of insanity, and I'll be the first to admit I've been there.
• When shooting video. In video, decisions about shutter speed and aperture have even more importance than with stills. For instance, in a still, 1/250 second might stop the action, but in a video, it gives it a jittery look that you might want in order to convey speed.

How it works

You set the shutter speed and aperture independently, and the camera meters the scene -- decides how much light is available -- and tells you if if the settings will produce an overexposed, underexposed or just-right exposure. You then adjust either or both of the settings until the meter reads the way you want. So the trickiest part is to actually remember to look at the meter.

How to use it

Turn the mode dial to the big "M".

How to read the settings

Shutter speed: "Shutter speed" indicates the amount of time the camera exposes the sensor to light from the scene. Compared to older cameras, most modern models now display the speed unconfusingly; that is, 1/2 is a half second and 2" is two seconds. If they don't, then the whole seconds might be displayed in a different color. In the viewfinder the camera usually drops the "1/" and indicates speeds greater than or equal to one second with a quotation mark. You might see a "B" on your mode dial, which stands for "bulb": in this mode, basically, the camera leaves the shutter open between button presses. Long exposures like that are good for astrophotography, for example.

Aperture: For most non-point-and-shoot cameras, the aperture is the opening in the lens that lets in the light. On a camera that has a quick-view screen it's usually the number next to "F" on the display. ("F" stands for "F-stop" or "F-number", calculated by the lens' focal length divided by the diameter of the aperture.) If there's no "F" it's usually the number next to the shutter speed on the display, and will likely show values between 1.8 and 32. If they're outside that zone, you probably have a really nice lens and already understand this stuff. Smaller numbers mean wider apertures, bigger numbers mean narrower ones.

Metering: The exposure readout is fairly straightforward. On a quick-settings screen, there's usually a big scale with smaller bars that show you the deviation from the camera's determination of a correct exposure. In the viewfinder, there's usually a similar view, but compressed to save space in some manner. (Some cameras use a similar display for showing a camera's deviation from level, so make sure you're looking at the right one.) Note that the camera's metering setting -- spot, matrix/evaluative, or center-weighted -- will affect what the camera perceives as a correct exposure. The reading doesn't have to be exactly centered at 0; you generally have some latitude a few units up or down as long as your camera is set to use 1/3-stop increments (in the menu system) rather than full stops.

How to use the settings

Changing the shutter speed and aperture values: On cameras with two dials, usually one on the front and one on the back, different manufacturers use different conventions for the primary adjustment dial. For instance, Canon uses the front dial to adjust shutter speed and the back for aperture, while Nikon uses the reverse. Lower-end cameras generally have just one dial and point-and-shoots sometimes use the navigation buttons. You might need to check your manual to figure out how to adjust one or both settings.

Now comes the harder part: understanding the relationship between the settings.

With the conceptual diagram above for reference, think of the bounding square as the camera-determined exposure, and the lengths of the triangles' sides the values of each of those settings; shorter segments mean less light for the exposure (narrower aperture, faster shutter speed, lower ISO sensitivity) while longer segments mean more light for the exposure (wider aperture, slower shutter speed, higher ISO sensitivity). As long as all the triangle vertices touch the sides of the square, you're just trading off among shutter speed, aperture and ISO sensitivity settings for a given exposure.

So if we use the example on the left as the starting point, in the two top examples we've fixed ISO sensitivity at that initial value; on the left we've increased shutter speed and decreased the aperture size by increasing the aperture value (remember, it's reciprocal), while on the right we've widened the aperture and decreased shutter speed.

If you throw changes ISO sensitivity settings in the mix (bottom), you can see that, for example, changing the ISO sensitivity gives you more flexibility over choices for shutter speed and aperture.

Where to start?

When you're beginning, there are a few ways to figure out what your initial settings should be. For instance, you can put the camera in Program mode, take a photo, and decide whether you like those settings, switch into Manual and either reproduce them or tweak them to your liking.

The way I figure out my initial settings is by considering the scene. My rules of thumb:

• For action, determine your shutter speed first, then ISO sensitivity, then aperture
• For medium to low light, set your ISO sensitivity first, then shutter speed, then aperture
• Under well-lit conditions and little movement, set ISO sensitivity first, then aperture, then shutter speed.

You may want to choose differently. For instance, I tend to prioritize shutter speed most of the time because I shoot a lot of moving subjects (cats!) and/or want to ensure I'll minimize camera shake. But I also shoot with a lot of good cameras that can handle relatively high ISO sensitivity settings. If yours doesn't perform well beyond ISO 800, for instance, you probably want to lock that down first. The whole point of Manual is that you get to prioritize what you think is important.

One thing to remember when performing visual trial-and-error is that the camera displays may not be quite accurate, especially when it comes to exposure; also, what may look like really dark, clogged shadows on the tiny LCD may have reasonable tonal range when viewed on a larger screen. You might want to turn on the camera's histogram display (look it up in your manual) to verify that it's not too shifted toward the shadows or the highlights, unless you want that effect.

The guidelines for choosing settings are pretty much the same as those for shooting in the Shutter- or Aperture-priority modes.

Choosing a shutter speed: I find between 1/80 and 1/125 second work in most cases with little motion; I chose 1/80 second as my slowest general setting because I know that's safe for me to handhold without shaking. You need to figure out what that setting is for yourself, because you don't want to drop below it thoughtlessly. By "thoughtlessly," I mean you really have to concentrate to handhold effectively as the speeds get slower: control your breathing, brace yourself against something, make sure image-stabilization is enabled, and so on. To stop action, starting at about 1/250 second and increasing as necessary seems to work as well.

The Internet is littered with rules of thumb about selecting shutter speeds depending upon the effect you want. Google it. Those rules were more important in film days, when trial and error was impractical, time consuming and expensive. Today, you can usually figure out within the first few shots what setting produces the image you want.

Choosing an aperture: Keep in mind that if you have a zoom lens with a variable aperture range (denoted as say, an 18-55mm f3.5-5.6 lens rather than 24-105mm f4), the widest aperture will decrease as you zoom in to the telephoto end regardless of your setting -- e.g., go from 18mm f3.5 to 55mm f5.6 -- and reverse toward your setting as you zoom back out to wide angle. With a lens like that, on anything smaller than full-frame you don't have a lot of flexiblity. For everything but studio-type work, if you're going to shoot with an inexpensive kit lens and want the closest you can get to a set-it-and-forget it choice, I vote for f5.6, at least in good light. That will ensure snapshot-quality sharpness of most things you plan to shoot, and will keep the aperture from changing as you zoom. An alternative is to set it f3.5 (or whatever the widest your lens supports) with the understanding that it will change automatically as you zoom, but it will automatically change to be set to the widest aperture possible for a given focal length.

If you want maximum sharpness throughout the scene and there's plenty of light, then f8 or f11 is a good choice. Try to stay away from f16 or higher on inexpensive lenses and small sensors, since sharpness tends to decrease past a certain point as other laws of physics intrude.

If you have a fast lens that supports apertures of about f2.8 or wider, there are some caveats to shooting wide open. First, the wider you go the harder it is to focus accurately; the smaller the zone of sharpness, the more difficult it is to keep the camera fixed on the appropriate point. This is especially true if you're depending upon autofocus. Also, cheap, fast lenses, like a typical 50mm f1.8, tend to produce fringing on the photos at their widest.

ISO sensitivity: If you're confident about the high-ISO sensitivity performance of your camera, you may want to leave this on Auto; keep in mind, however, that some higher-end cameras won't let you use Auto ISO in Manual mode. The ability to do so is becoming more popular in that segment, though, as a way to allow for constant exposures when shooting video -- it lets you set the shutter speed and aperture and vary the ISO sensitivity as lighting conditions within a scene changes.

However, as sensor size decreases, out-of-focus areas tend to become increasingly unattractive; increasing ISO sensitivity exacerbates the artifacts in those areas. So if you'll be pixel-peeping your photos, you may want to err on the side of narrower aperture/slighly deeper depth-of-field or to shoot at the lowest ISO sensitivity possible. As with the priority modes, the camera will always choose the lowest available option that matches your chosen aperture when set to Auto ISO. However, if you're going to use it, see if your camera has a menu option to set a prescribed range of values it can choose from. That's especially important on the high end, since most consumer cameras don't do very well above ISO 6400, regardless of what their specifications may indicate.

If you plan to adjust it manually, you always want the lowest setting possible that gives you enough flexibility to enable you to choose other important settings.

You can usually figure out within the first few shots what setting produces the image you want. Just remember:

• Increasing the aperture number setting narrows the aperture and broadens the area of sharpness for a given focal length and distance from the subject; increasing the shutter speed stops motion.
• Decreasing the aperture number widens the aperture and shrinks the area of sharpness for a given focal length and distance from the subject; decreasing the shutter speed increases the appearance of motion and increases the chance for camera shake.
• Increasing the ISO sensitivity boosts the amount of light the sensor will register, but also boosts the amount of color noise.

More important settings to consider

• Metering mode
  Because the feedback you get from the camera to determine what your other settings should be relies on what the camera perceives as a correct exposure, if you want something darker or lighter you'll have to tell the camera. You can do this either by changing the metering mode -- changing the way the camera decides what "correct" means -- or using exposure compensation, which simply increases or decreases the brightness by a specified amount after the camera has made its choice. These settings become important in cases where "correct" is too dark, such as happens with snow scenes or backlit subjects, or too light, when important details of the image may be blown out.
• Autofocus
  No autofocus system I've used has been able to pick the correct subject to focus on 100 percent of the time; only you know what's important in the frame. Many of the advances in autofocus over the past few years -- most notably face detection -- have been designed to compensate for that fact. So try to use autofocus options that limit the area, like expanded center point autofocus, if it's available, or center-point autofocus.

What are the drawbacks of Manual mode?

Just one: It takes a lot of practice before choosing settings becomes instinctive, which can slow you down in unfamiliar situations. That's why I like suggestion the "D'oh!" approach to starting out; that moment when you're photographing something for the Nth time and you suddenly realize that Manual mode would be easier than the semiautomatic mode you've been relying on.