The technological advancements in photography could hardly be imagined by photographers using slow film with manual focus, non-stabilized lenses just 20 years ago. Go back further and cameras did not even have built-in meters. Photographers had to use an incident meter to determine a proper exposure, then dial-in the settings manually. Everyone had to know how to use manual mode!
Above image: Black-billed Magpie; manual mode; 1/ 2,000-second; f/8; ISO 800
The above image was the ultimate exposure challenge. A high-contrast bird was flying in front of radically different backgrounds in rapidly changing ambient light. The background consisted of pale blue sky, sunlit snowcapped peaks, shadowed woods, and more. In addition, the sun was peaking in and out between fast-moving clouds. No auto-exposure mode was going to get the job done, so I switched to manual mode, and spun the shutter dial wildly back and forth as the sun came and went. Today’s bird photographers have it relatively easy, but few are taking full advantage of their cameras’ advancements. Let’s explore the various exposure modes and determine which one(s) are right for you.
Manual Mode (M)
Manual mode provides precise control but is a relatively slow process in many situations. You, the photographer, have full control and make all of the exposure decisions. You set your desired shutter speed and aperture along with a corresponding ISO to make a proper exposure. All of this pushing of buttons and turning of dials takes time while birds are often moving fast. Manual is an excellent mode in consistent light, for birds in flight, and any time a subject is moving rapidly past changing backgrounds. You determine the exposure, then set it and forget it, unless the light falling on your subject changes. Manual, however, is tedious at best in rapidly changing light and you must be keenly aware of subtle changes in light intensity. You will have to make regular exposure adjustments as the sun grows higher (or lower) in the sky and when clouds move in to block the sun temporarily.
Manual Mode with Auto ISO (Ma)
There is technically no Ma exposure mode on your camera—I just made that up. It is simply manual mode set in conjunction with auto ISO. Interestingly enough, Nikon users have been touting the benefits of Ma mode for some time now, while you never hear mention of it in Canon circles. Ma does indeed work with Canon cameras, too. As you might suspect, in Ma mode the photographer sets both the desired shutter speed and aperture while the camera sets a corresponding ISO to make a proper exposure. Beyond that Ma behaves exactly like an auto-exposure mode and, thus, exposure compensation may be necessary (see next section). Unfortunately, dialing-in exposure compensation is not direct dial and requires an extra step. Worse yet (for Canon users, anyway) the exposure compensation only shows in the viewfinder while in the process of setting the compensation. Activate the shutter and the compensation amount disappears from the viewfinder. I have no firsthand experience with this technique with Nikon, but have read it works much the same as Canon. In all reality, Ma is just another auto-exposure mode.
Auto-Exposure Modes
With the arrival of in-camera metering systems, various auto-exposure modes became available. It is important to remember that when working in any auto-exposure mode, it is the camera that is making at least some of the exposure decisions for you. The in-camera meter makes exposure choices based on the assumption that the area covered by the meter averages to a mid-tone. That is one HUGE assumption! In many instances, the photographer will have to make decisions to input exposure compensation to help the camera come to the right exposure. The amount of compensation necessary depends on a wide variety of variables. The necessary compensation is affected to varying degrees by the tonality of your subject and background, your camera manufacturer, as well as the light intensity and direction at the time of exposure. The meter can even vary between different models from the same manufacturer. In essence, the photographer has to become intimately familiar with how their camera responds in a variety of situations. Despite it being exceedingly difficult to dial-in exposure compensation while tracking a fast-moving bird, one of the auto-exposure modes might be right for you, especially in rapidly changing light.
Program Mode (P)
Program mode is the most automated of the auto-exposure modes. You are responsible for selecting your ISO. The camera then chooses a shutter speed and aperture for you. It will tend to set a faster shutter speed and wider aperture when longer lenses are mounted. With a wide lens in the same light, a slower shutter with a smaller aperture is chosen. I almost never use program mode for bird photography, but it is useful when using flash as main light in low light or nighttime situations. Check your camera’s manual or experiment to test but, in most instances, the camera will set a wide aperture and 1/60 of a second as the slowest shutter when a flash is mounted.
Aperture Priority Mode (Av in Canon, A in Nikon)
For the past quarter century or more, Av mode has been the auto-exposure gold standard for bird photographers. Using Av certainly made a lot of sense when we were stuck using slow films. I would load my film and set the ISO to 100 in-camera to match the film. ISO 100 would rarely result in a fast shutter speed, unless working nearly wide open and in full sun. Most of the time, I would set the widest available aperture, such as f/4 or f/5.6. The camera would then meter the scene as a mid-tone, leaving me stuck with whatever slow shutter speed resulted. In Av it is easy to stop the lens down for additional depth of field, should you be photographing a bird at point blank range, or attempting to get two individuals both in sharp focus. This, however, results in an even slower shutter speed. Today this is less of an issue since we can simply increase the ISO as needed when the light starts to fade or we desire a bit faster shutter speed for fast action. Today I recommend Av as the best auto-exposure mode for anyone who is not happy with the high ISO noise performance of their camera and for those still shooting film (yes, there are still a few out there).
Shutter Priority Mode (Tv in Canon, S in Nikon)
Shutter Priority is now my default exposure mode. When going for a drive or a walk and not knowing what subject I might encounter, I select shutter priority with auto ISO. I set the shutter speed I desire, generally around 1/1,000 of a second in good light, and allow the aperture and ISO to be selected by the camera. In general, my Canon cameras will choose the widest available aperture and then increase the ISO as needed when I have a long lens mounted. With the excellent noise performance of today’s modern digital cameras, I have the flexibility to obtain the shutter speed I need instantly when I suddenly encounter fast action. Fast shutter speeds are mandatory whether photographing bathing shorebirds, spinning phalaropes, or wave chasing Sanderlings. In these instances, I am willing to sacrifice a bit of extra noise to obtain a faster shutter (near 1/ 2,000 of a second to freeze most fast action).
Shutter priority with auto ISO can also be used to hold back the shutter speed when creating intentional motion blurs. Depending on the speed of the subject and the desired effect, I can spin the shutter dial to quickly get to a slow shutter. The ISO will go to the lowest setting and the lens will stop down the aperture to get me to the desired speed. When shooting action at slow shutter speeds, as with this Semipalmated Sandpiper, it is critical to track precisely while holding the lens as steady as possible. Note, I had used a menu function to lock out ISO 100 for the hovering sandpiper image. Otherwise ISO 100 would have been selected at f/20.
I use shutter priority in one more way. When using fill flash, I use Tv to hold the shutter speed back to about 1/500 of a second. Unfortunately, I find that adding a flash to the mix with auto ISO makes the camera behave unpredictably. I never know what aperture will be selected, which I find totally unacceptable. Insert ISO safety shift, which has been an available feature in the custom function menu of most Canon DSLRs for a number of years. I set ISO 100 and enable ISO safety shift in Tv mode. Due to the low ISO, the lens will almost always need to open up to wide open to get to 1/500. If opening the aperture wide open still results in an under-exposure, then the ISO will be increased automatically. Remember, in Tv mode it is you who selects the shutter speed and the camera that selects a corresponding aperture value to get a correct exposure.
Holding the shutter speed back has several benefits when using fill flash. While 1/500 isn’t blazing fast, it is fast enough to freeze most action. In good light you will not need an overly high ISO, so the noise levels will be low. The final benefit of a slower shutter speed is that the flash will use less power and recycle more quickly, giving a nice kiss of light in more consecutive images. Today I use fill flash mostly in bright conditions to reduce shadows. On overcast days, I prefer the natural look of even lighting.
How does all of this relate to my shooting preferences? Today, it means most of the time you will find me working in shutter priority with auto ISO since I am willing to deal with some noise in favor of full control of the shutter speed. The exception would be that I choose manual metering when my subject’s movement takes it in front of backgrounds of varying tonality. In bird photography, seconds count, so I choose to utilize whichever mode will most quickly and accurately get me to, and keep me at the correct settings.
