Using your camera’s programmable shooting modes, like Program, Aperture Priority, Shutter Speed Priority, and Manual shooting modes (PASM) can understandably be a daunting and often baffling process. The numbers can be confusing, the options overwhelming, and the results (at least initially) unpredictable. But with practice and perseverance, these 4 programmable shooting modes will eventually become your best friends, especially when you master their various intentions, and enjoy the results of photographs where you took full control over your image’s appearance. Want to separate your subject from a distracting background, or smooth out the motion of a waterfall, or perhaps you want to simply use your camera’s white balance or ISO settings for creative effect, by deliberately introducing film-like noise or “warming up” an otherwise cool appearing photo. In these cases and more…the programmable shooting modes are your solution.

Now, as we’ve intimated, there’s a time, a place, and a shooting scenario for each of the 4 programmable shooting modes, and eventually we’ll cover all of them in forthcoming articles, but for me, and dare I say most enthusiast to pro-level photographers, Aperture Priority is the shooting mode my camera is in about 90% of the time. Its uses are many, but Aperture Priority is typically well suited for general photography, macro photography, street and documentary photography, and landscape photography. The reason? Because of all the shooting modes, Aperture Priority provides the easiest access to controlling the characteristic that has one of the biggest potential aesthetic impacts on your pictures, depth of field.

With that, let’s break down how it works and how to use it in 7 easily digestible steps.

Aperture Priority is the “A” or “Av” on your camera’s shooting mode dial.

To use Aperture Priority, look at your camera’s shooting mode dial (or virtual one in the case of several newer cameras that lack a physical shooting mode dial) and locate the big letter “A” or “Av” on Canon cameras. Set the camera to that A or Av, to begin shooting in Aperture Priority. While I’m tempted to say that you’re now prepared to shoot in Aperture Priority, it is important to note that Aperture Priority, as with the other programmable shooting modes does require user input over additional camera settings, like white balance (WB), ISO, and metering options. Typically most users will opt for auto white balance (AWB), and most will also opt for an Evaluative Metering (or Matrix Metering on Nikon cameras) option, so other than ISO, which we’ll cover down below, you can essentially get started with shooting in Aperture Priority. Of course WB and Metering can play pivotal roles in your image’s appearance and we plan on covering both in future articles, but for now let’s assume AWB and Evaluative Metering.

Aperture Priority gives you control over Depth of Field

Now that your camera is set to Aperture Priority you’re probably wondering what it is exactly that you’re controlling. Essentially you’re controlling the diameter of the aperture (or opening) of the lens you’re using, be it one you’ve attached, or as with many compacts, the one permanently attached to your camera. A larger aperture equals more light hitting the sensor which amounts to a brighter exposure (all other camera settings being equal) versus a smaller aperture. But perhaps more importantly, the larger the aperture is, the less light rays are “collimated”, a term that describes how parallel light rays are next to each other. At narrow aperture settings (small openings), light rays are more collimated (picture a cylinder of straws held together by a rubber band), the end result on your image being that more of your picture appears to be in focus relative to your selected plane of focus. A wider aperture diameter results in uncollimated light rays, with the result being the camera only focuses on small portion of the image, essentially light rays with the same focal length as the focal plane.

This dynamic of more or less of your image appearing in focus is termed “depth of field” and controlling it has a huge impact on how your pictures look. Think of that “field” as the distance between you and the theoretical end of your “background”. Now picture your focal point as a plane or sheet of glass inserted into that field. A shallow depth of field means that very little in front of or behind that plane of glass will appear to be in focus, while a longer or deeper depth of field will make more of your image behind and in front of your focal plane appear in focus. If you want to blur out a distracting background to isolate your portrait subject, you’d want to use a wider aperture (a bigger opening), to create shallower depth of field. Conversely for the typical landscape, you’d typically want to use a smaller aperture, which produces more collimated light rays hitting your camera’s sensor, and thus creates a longer/deeper depth of field, where nearly everything, including in front of and behind your focal plane, appears in focus.

Naturally you can opt for a depth of field anywhere in between, that’s the beauty of Aperture Priority. Gently blur the background or obliterate it. Pull everything into focus, or soften the scenery in the background ever so slightly. Aperture Priority gives you the control of what appears to be in focus, and once you capitalize on that power, you’ll be loathe to give it up.

There’s one more thing. Many photographers quickly come to enjoy the pure aesthetic value of the out of focus areas in their captures. The aesthetic quality of out of focus areas in your images is referred to as “bokeh” and it can be a beautiful, if subjectively so, photographic “subject” in its own right. Getting great bokeh generally comes by working with larger apertures, typically with the lens wide open or close to it. The key to exploring it though will be using…you guessed it…Aperture Priority (and the right lenses/camera more on that at the end).

Finally, there are several other factors that can play an impact on depth of field, including your distance to a subject, the magnification of the lens, and even sensor size. Regardless, controlling your camera’s aperture will be the key to exploiting depth of field, and of course, Aperture Priority will be your way of doing so.

In Aperture Priority a smaller number equals more light (brighter exposure) and less depth of field

We mentioned it above, but by now is should be clear that a larger aperture both allows more light into the camera and creates a shallower depth of field. What can cause an enormous amount of confusion for beginners is that the aperture values, measured in “F-stops” are rather unintuitively arranged so that the smaller the number, the larger the diameter of the opening is. That is to say that F2.8 is brighter and offers shallower depth of field than F5.6, and obviously F5.6 offers less depth of field than F11, F16, and F22. The best method to get past this confusion is to simply keep using Aperture Priority, explore various apertures in your work, and then examine the work and the EXIF data to show what settings had what effect on your captures. Until it sinks in, I found it easiest to stop thinking of aperture as an exposure setting, and instead think of it for what it does…remember? It controls depth of field, thus a smaller number (F1.4) equates to less depth of field, less in focus, and a larger number (F16) equals more depth of field, more in focus. After all, you’re using Aperture Priority to control how much of your images will appear to be in focus, not because one aperture setting is brighter than another.

In Aperture Priority the camera is controlling your shutter speed

While you tinker with depth of field in your images, your camera is trying to optimize exposures by automatically controlling your camera’s shutter speed. When your aperture gets wider, the shutter speed gets faster. More light comes through a larger opening faster, so the camera compensates by closing the shutter faster. Logically a smaller aperture leads the camera to leave the shutter open longer, because less light is hitting the shutter. Now this process is automatic in Aperture Priority and generally is of no consequence to the user, but there are exceptions. The most frequent problem is that a selected aperture, typically the more smaller settings (i.e. the larger numbered F-stops like F11, F16, etc…) can cause the shutter speed to slow to such a degree that images are blurred, not blurred from shallow depth of field, but blurred because of small camera movements, or motion blur from the intended subject. In broad daylight for most general photography this shouldn’t be an issue, but this concern does become crucial for landscape photographers who typically work at very small apertures for maximum depth of field, often early or late in the day when ambient light is waning. Because of this issue, a tripod becomes critical for taking sharp images, and even under bright conditions, most landscape photographers would benefit from using a tripod when using very small apertures.

Somewhat strangely, bright ambient light can create problems when using wider apertures, because many cameras won’t have a shutter speed fast enough to produce a proper exposure. If you’ve ever encountered an issue where no matter what you did you couldn’t stop your images from turning out overexposed (too bright), it was probably because you were using an aperture setting too wide for your camera’s shutter speed to compensate for. The solution here is adjust to a smaller aperture, but some photographers turn to neutral density filters, think sunglasses for your camera lens, to trick the camera into slower shutter speeds.

In some scenarios one can use the aperture’s effect on shutter speed to their advantage. One example comes in the form of taking pictures of waterfalls. Typically most photographers like the smooth effect of the silky waterfall created by using longer shutter speeds. With a camera on a tripod, the landscape surrounding the waterfall is perfectly sharp and clear, while the water is nicely blurred. Setting the camera to its smallest available aperture is usually good enough to induce the effect, say F16 or F22, and has the benefit of producing maximum depth of field, always a plus in landscape work. For sports photographers, knowing the camera offers faster shutter speeds at the widest opening, means they’ll frequently use their cameras at F2.8 or faster/wider, which just so happens to nicely isolate their subjects from their backgrounds, while “freezing” them in mid motion. Note in both cases there’s a desire to control depth of field, so while one could use Shutter Speed Priority (and a lot will do this), many photographers will opt for Aperture Priority and adjust their ISO settings to get proper exposures.

Aperture Priority can be tweaked with exposure compensation

Unlike manual shooting mode, in Aperture Priority your camera is relying on your camera’s metering system to make what it considers a proper exposure. Describing how a camera’s metering system works and how to use the various metering options is definitely a topic in its own right, but suffice it to say, most photographers will frequently want to overide the camera’s best determination of what a proper exposure is, and that’s done via exposure compensation. Exposure compensation is adjusted a myriad of different ways on various cameras, but frequently the setting is represented by a positive sign over a negative sign, though you’ll need to consult you specific camera’s manual for exact details. Typically most cameras offer easy access to exposure compensation as a physical camera button, because it provides the easiest method of quickly adjusting exposure. If we think of exposure, or the brightness or darkness of your capture, exposure compensation is the easiest to understand method for either adding more light or subtracting more light, based on your aesthetic preference. Note the camera has made what it believes is the proper exposure, based on the metering mode you’ve selected, where your focal point is, and the amount of contrast in your composition… exposure compensation is your means to correcting the camera’s choice. A positive exposure compensation brightens the image, by adding more light. A negative exposure compensation darkens the scene, subtracting light.

So remember, take your shot using your desired aperture for your desired depth of field. Then adjust your image when needed, adding or subtracting light via exposure compensation. Note that it’s important to realize that what the camera is actually doing is adjusting the shutter speed behind the scenes to let more or less light through to the sensor by staying open longer or shorter (in Shutter Speed Priority the exposure compensation adjusts the aperture setting behind the scenes, and there is no exposure compensation in Manual shooting mode). It may appear to be a magical brightening or darkening control, but the effects on camera shake and motion blur that we mentioned above do have to be taken into account. Still for me, this is the beauty of Aperture Priority, once your desired amount of depth of field is selected, all you need to do is adjust exposure compensation when needed or desired.

Aperture Priority can be further tweaked with ISO

In poor outdoor light, indoors, and after the sun goes down, you’ll frequently run into situations where you simply don’t have the shutter speed necessary to take sharp images. This can happen even at the lens’ widest/fastest aperture, and even many modern camera’s image stabilization technology may not be able to overcome it. When this happens you’ll need to resort to your camera’s flash, which can be distracting and unappealing photographically, or better, adjust your camera’s ISO setting. First lets start with a rule of thumb, ideally you want your shutter speed to be at least 1 over the current focal length of your lens. If you’re using a 50mm lens, try to make sure that the shutter speed your camera is using is 1/50 or faster, and remember we’re talking the 35mm equivalent focal length. If you’re using an APS-C DSLR with 1.5x crop factor, a 50mm lens is equal to 75mm, and you’ll get best results by shooting 1/75 or faster. If the shutter speed is slower than the 1 over focal length trick, adjust the ISO higher till the shutter speed is fast enough.

To briefly explain, increasing ISO increases the sensor’s sensitivity to light, making for a brighter image while keeping the same aperture and shutter speed values. Most photographers will already know that doing so introduces image noise to your captures, the higher the ISO setting, the more noise in your image. For many, the added noise is a worthwhile trade off for sharper images, but how far you’re willing to take it is up to you and your camera’s ability to control noise at higher ISO settings. The good news is that many contemporary cameras are very good at minimizing noise at higher ISO settings, so don’t be afraid to explore what in the past may have been a truly last resort option.

Aperture Priority allows you to use your lenses to their best advantage

Finally, Aperture Priority can have one further benefit that shooting in AUTO may bypass. The fact is that even very good and expensive lenses have their strengths and weaknesses, and these areas have usually been well defined by various tests and analysis, most of which is easy enough to find online. When we review lenses here at CGG, we’re able to determine at which aperture settings a given lens is the sharpest and least sharp. Most photographers know that lenses aren’t their sharpest wide open, for example F2.0 can be much sharper than F1.4. But many may not realize that due to diffraction, lenses lose their sharpness at their narrowest apertures, for example, we tested a lens that dropped off substantially after F11, leading us to infrequently use it at F16 even when the situation desired it (landscape work for example). Issues like light fall-off (vignetting) and chromatic aberrations too are worse at certain apertures, the point being using Aperture Priority allows you to work to your lens’ strengths, and around its weaknesses, which can bring a huge impact when you’re looking for maximum sharpness, avoiding diffraction, and minimizing optical flaws.

Conclusion

We hope you’ve learned a thing or two here in our first edition of Camera Basics. Hopefully now you have a better understanding how Aperture Priority works and how to make use of it, and given some practice, we’re sure you’ll find your camera set to Aperture Priority as often as ours is. Before finishing, we’d add that taking full advantage of Aperture Priority and depth of field can be greatly enhanced by using cameras and lenses that offer plenty of depth of field. Yes, this basically works out to: you’ll be wanting “fast glass”, but that doesn’t have to equal lots of money, or even a DSLR camera. Our favorite compact of the year, the Olympus XZ-1 has an impressive F1.8 lens, and if you have a DSLR and haven’t bought a 50mm prime lens, do yourself a favor and get one now. Often they’re relatively affordable, they’re compact, are perfect for portrait and street work, and can be F1.8 or faster, basically a great way to really explore depth of field at minimal cost. Check out the following links to browse various 50mm lens offerings for the major camera systems, several can be had for just a couple hundred dollars or less!

• Olympus XZ-1 10MP Digital Camera
• Canon EF 50mm f/1.8 II Lens
• Canon Normal EF 50mm f/1.4 USM Lens
• Nikon AF-S Nikkor 50mm f/1.8G Lens
• Nikon AF-S Nikkor 50mm f/1.4G Lens
• Sony SAL-50F18 50mm f/1.8 DT AF Lens
• Sony SAL-50F14 Normal 50mm f/1.4 Lens
• Pentax Normal SMCP-FA 50mm f/1.4 Lens
• Olympus 25mm f/2.8 ED Zuiko Lens
• Olympus M. Zuiko Digital ED 45 mm f/1.8 Lens
• Olympus Zuiko Digital 35mm f/3.5 Macro ED Lens

All of the options above are available from B&H Photo, and combined with what you’ve learned above about Aperture Priority, should set you up for taking eye-catching photos in no time. It may seem complicated, but trust us, once learned, you’ll rarely find yourself heading back to AUTO ever again.