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Using autofocus like a pro: Tips to achieve perfectly sharp images.

Photographed by Kaleb Friend.

Picture this: You are in a crouching position, your angle is perfect, and your subject is framed as flawlessly as the Mona Lisa herself. Snap. You take your shot. You rise to a standing position, patting yourself on the back for nailing what was probably the most dramatic, emotion-filled moment in the entire wedding reception. As you leave that evening–despite the exhaustion that comes from shooting for ten hours straight–you feel nothing less than victorious. 

That is, until the next morning. When you sit down at your desk to review your self-perceived excellence, you find that the shot is just ever-so-slightly out of focus. 

Feel that sinking feeling in your gut? 

Don’t worry, we’ve all been there. In fact, this is my own photographer sob story–it’s the kind of moment that’s hard to forget!

When a photo lacks proper focus, it runs the risk of compromising the mood or intended subject of the shot. Although an intentionally blurred or out of focus picture can have its own kind of magic, the accidentally ever-so-fuzzy ones are far less likely to elicit the vivid emotional response you want from your clients.  In the realm of modern cameras with abundant cutting-edge features, one might assume that achieving a tack-sharp photograph should be a straightforward endeavor. 

However, autofocus is anything but simple. Knowing how and when to use it is more than half the battle.

So, let’s dig into the hocus pocus of autofocus, understand what it is, and see how it works!

What is autofocus and how does it work?

To put it simply, autofocus is a tiny computer inside your camera that automatically focuses your lens to (hopefully) achieve the sharpest image possible. While control for all of this is located in the camera itself, the majority of contemporary cameras utilize autofocus motors within the lens rather than the camera body. 

To pinpoint where you want your focus to land, your camera uses AF (short for AutoFocus) sensors. This tiny AF processor does the job of measuring the subject’s focus distance and communicating enhancements to the sensor. Once everything is set up and calibrated, the processor adjusts the camera lens to alter the distance. Even amid these processes, continuous improvements to the focus also take place. 

This is all incredibly complex, yet your camera does it all seamlessly the majority of the time. 

Active vs. passive autofocus.

Autofocus systems can be active or passive. What works best for you might depend on your level of experience, your gear and preferences and the subject of your photographs. 

Active autofocus: Infrared in point-and-shoots.

Most less expensive point-and-shoot cameras employ an active system. This works by emitting an infrared signal to determine the ideal focus for each picture and is best for snaps up close. Because active systems don’t rely on image contrast, they can be effective even in dark environments. 

The fault with this system? They are susceptible to problems related to their reliance on infrared light. Flames in a campfire, or those sparklers in that gorgeous wedding sendoff, can interfere with the system and cause incorrect focus. Dark subjects like a groom’s tux or the black lab your client wanted included in their sunset family portrait session can absorb the infrared light, keeping it from reflecting back and giving you proper focus. 

Passive autofocus: Phase and contrast detection in DSLRs and mirrorless. 

The majority of modern cameras (DSLRs included) rely on passive focus. Using digital computer analysis to discern the subject’s distance, the camera scans the scene and orchestrates a back-and-forth movement of the lens in pursuit of the holy grail of focus. 

Within the passive autofocus system, there are two types of detection: phase and contrast detection. The most common autofocus in DSLRs is phase detection, where the camera dissects incoming stimuli into pairs of images and compares them. The camera sensor carefully and quickly examines the images reflected by the camera mirror and transmits the data to an internal computer for further evaluation. If the images don’t align, it means they’re out of focus. 

Not only does all this happen incredibly fast, but the accuracy is unparalleled. Smartphones, mirrorless cameras, and certain modes in DSLRs, like live view or video, go for contrast detection, which uses the light falling onto the main camera sensor to provide input for focus. 

When to use autofocus (and when not to.)

Without a doubt, autofocus is best for live events where your subjects are in motion. Wedding ceremonies, for example, can be notoriously unpredictable. Life lives in the moments unplanned–and your clients want that captured. The last thing you want to be worried about is pulling focus at times like these. 

Autofocus is also ideal for sports activities of any kind because people or objects are moving constantly. The focus tracking capabilities on several of the newer cameras introduced within the last 1-2 years is practically invaluable to photographers to specialize in sports photography. 

Finally, autofocus is typically employed with video, either handheld or on a gimbal, to help keep that focus while creating dynamic movement-based imagery. 

Manual focus: When it’s a must.

Autofocus gets better and better with every passing year, and today’s digital camera is more powerful than ever thanks to the help of digital technology. 

Even with these significant improvements, manual focus continues to reign supreme for a lot of photographers. You will find that autofocus works perfectly most of the time, but shooting manually is still an important skill to have in your toolkit for certain scenarios. As you become more experienced as a photographer, and the more familiar you get with your equipment, choosing when to use manual or autofocus will become second nature. 

There are several instances in which using manual mode will give you a better chance at a sharper photograph. 

• Minimal light situations: Autofocus will still frequently struggle to find the focus or intended subject. Whether you are shooting the night sky, or a shadowy wedding reception lit by the DJ’s colored lights and bursts of strobe lighting, manual focus will be your best bet for beating the dreaded lack of sharpness. 
• Low contrast conditions: Photographing a lighthouse near the ocean, draped in a shrouded veil of a Maine morning fog, or a country road settling into a dewy summer night where the light and the dark are almost touching…both good examples of when focusing manually will benefit the final image.  
• Intricate and detailed scenes: With projects such as Macro Photography, precise focus is crucial and even slight movements like breathing can affect the sharpness of the image, manual focus becomes particularly essential. 
• Shooting through an object: When capturing shots that are made through an object, such as a fence at a baseball game, you’re adjusting your focus to capture subjects that are positioned beyond the immediate foreground elements closest to your camera, which can confuse your lens. With manual focus, you have more control and a better chance of catching that slide into home base! 

Autofocus will get the job done in most shooting scenarios, yet the proficiency to confidently switch it up to manual mode can prove absolutely invaluable. 

While autofocus typically meets the demands of most situations, having the ability to manually control your focus becomes crucial in instances where the technological capabilities of your lens may fall short. 

Understanding autofocus modes.

When you are just starting out, choosing the right autofocus mode may seem as complex as a high school AP Calculus exam question (okay, maybe not quite that bad.) Choosing the wrong AF mode might mean a batch of blurry, disappointing photos of a special day or event. But fear not! As with anything else, practice and know-how make all the difference. 

Let’s explore each autofocus mode, and when is the best time to employ them:

Auto Area Focus Mode: All points, camera-driven.

All focus points are firing, and they are on the hunt for the area of highest contrast or closest subject to the camera to focus on. This sounds ideal, doesn’t it? Unfortunately, leaving it up to your camera to do the driving doesn’t always result in a great outcome. Unless you have a snazzy new camera that will detect specific items (like people) it will likely pick the closest object in front of it, and if that isn’t what you want to capture, you will end up with a fuzzy photo focused on the wrong thing.  Personally, I do not recommend using this mode in any shooting scenario–if you decide to give it a try, save it for personal projects rather than paid shoots. 

Single-Point AF Mode: Pin-point control for static subjects.

Just one focus point is activated and you move it around to accommodate your subject. This really will give you control over where the lens is going to set down its focus and is best used for subjects that are not on the move. Portraits, landscapes, food photography, or product photography are all good matches for single-point area AF mode. 

Dynamic Area AF Mode: Tracks moving subjects.

You pick the spot to focus on, and if your subject decides to wander off, no worries – the camera’s got your back. The lens will track it wherever it goes. This mode is perfect for action-oriented photography like sports, wildlife, or toddlers (as a mom of four, I speak from experience here.) When you’re dealing with unpredictable moments, using dynamic AF seriously boosts your chances of nailing that perfect shot–like that exit down the wedding aisle.

Group Area AF Mode: Zone-based focusing for action/wildlife.

This mode is all about the zones. Instead of pinpointing just one spot to focus on, you get to choose an entire area where you expect the action to take place. The camera will kick into gear using multiple focus points within that chosen zone, hone in on the subject, and capture the shot. Again, this one is great for wildlife–and if you like photographing birds, this one’s for you. 

Eye AF Mode: Automatically finds and focuses on eyes.

Let your camera do all the eye-catching in this mode! When the camera is set to eye AF, it automatically focuses on a subject’s eyes even if it is in motion. This mode is especially great for pets and kids who are always on the go within the frame.

Advanced autofocus techniques.

Focus Lock: Focus lock lets you zero in on a specific part of the scene or a subject to nail the exposure. Activating focus lock is pretty straightforward–simply press the shutter button down halfway. This technique is applicable across various focusing setups, but it shines when using single-point AF. It proves most advantageous when shooting subjects who are off-center. 

Tracking Moving Subjects: Continuous tracking taps into the camera’s predictive AI and is great for pets, kids, birds…anything on the move. Your camera’s processor uses its magic crystal ball to foresee the future movement of your subject, adjusting the focus along the way in little bursts. As you are following your subject with your lens, the system crunches numbers, considering factors like size, speed, distance, and direction of travel to predict where they will go next, ensuring your shots stay sharp and right on target.

Autofocus challenges: Put your skills to the test.

Now that we have all of this knowledge in our pocket, let’s put it to work with a little single-point and continuous autofocus challenge!

Challenge 1: Portrait sharpening with Single-Point AF 

1. Choose a willing friend, family member, or my personal favorite, bribe one of your children. Select a location with a clean backdrop so that it does not compete with your subject. Good natural light here is key–not too dark, not too bright.
2. Choose a wider aperture such as f2.8 to achieve a shallow depth of field. This will create that dreamy background blur.
3. Move into single-point AF mode. Put the single autofocus point over one of the eyes. By doing this, the most critical area of a portrait will be sharply in focus.
4. Frame your subject following basic composition principles such as the rule of thirds. Take multiple shots, playing around with different angles and poses while keeping the focus on where it matters most- the eyes.
5. Explore how distance and composition affect the background blur. Create a beautiful bokeh by experimenting with different background elements and distances.
6. Every few shots, look at what you have captured on your camera’s LCD screen. If necessary, adjust the focus point, composition, or settings to achieve better results. Don’t forget to pay attention to the balance between your subject and the blurred background.
7. Thank your willing participant (or settle your debt), and head off to review what you just did! Note the feelings of euphoria when you see one of your perfectly focused images. What worked and what didn’t? What will you do differently next time? 

Challenge 2: Freezing action with continuous autofocus.

1. Choose a location where a lot of fast-paced movement is taking place. This could be a sporting event, dogs playing at the park, or a bustling street. 
2. Start with a shutter speed of at least 1/500 or faster to help freeze the action. Depending on the speed of the subject, you may need to make adjustments.
3. Change your camera setting to continuous autofocus (AF-C or Al Servo depending on your camera), and switch up your AF mode to dynamic for more spot-on tracking.
4. Where do you think your subject will go? Make a little prediction. Press the shutter button halfway to activate continuous autofocus. 
5. Get ready to pounce. I recommend the burst mode because it will increase your success rate, and it makes a really fun sound. 
6. Just like with the first challenge, change your composition or distance to get a variety of images.
7. After you are done shooting, take a peek at your images on the computer. Analyze each one for focus accuracy, how you framed the shot, and the timing. Make a note of which images you nailed, and where you see room for improvement. 

Time to sharpen your focus!

Autofocus is a fascinating and complex technology that continues to evolve and improve by leaps and bounds. 

While not without its shortcomings, like all things with many moving parts, it is a very powerful and useful tool. In our journey as photographers, technology becomes a key part of the love language through which we express our vision. 

It’s not just important; it’s essential to understand how this moment-capturing machinery works, allowing us to push the boundaries of our artistic endeavors. Wishing you crystal-clear captures, fellow photographers–stay sharp!

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