Everything you need to (finally) nail your focus
The following lesson is taken from Module 4: Camera Operations in The Photo Fix For Teens.
Enrollment is OPEN through 1/29/21!
WHAT WILL I LEARN:
- The difference between out of focus and blurry pictures
- How focus differs from sharpness
- Three big contributors to focus
- Considerations to nailing focus with YOUR camera
This one ranks right up there amongst the most common of questions: “my pics aren’t in focus…can you help?” Well, it turns out there are many reasons for a missed focus. And since it’s a poplar topic, we had better discuss them all.
After we’re done, you’ll know exactly what you must do in order to nail your focus. Every time.
This is a ginormous lesson. To help, here’s a lesson table of contents:
- Out of Focus vs Plain Blurry
- Out of Focus vs Depth of Field
- Focus vs Sharpness
The Big 3 of AF:
- Light Level
- Contrast Level
The Step-By-Step Method
- Use ONE focal point (not all of them)
- Make sure that focal point is a “cross-type” sensor
- Use correct AF Mode
- Focus on area of contrast
- Recompose and Fire
- Be STILL
- See Clearly
- There’s always Manual
- What to do if you’re still out of focus.
Out of Focus vs Plain Blurry
First thing’s first. We need to be able to decipher between out of focus, and blurry. Because the two are subtly different on paper, but drastically different in how to fix.
Out of focus pics will still have something in the image that’s in focus, just the wrong thing. For example, this pic is clearly back focused:
This image is quite clearly back focused.
And this pic is just plain blurry:
Blurry pics affect the entire picture, edge to edge, front to back. Sometimes they even show a bit of ‘drag’ that looks like camera shake. In fact, it probably is camera shake. In which case you need to fix it by shutter speed, and it’s all explained here.
All to say, the fix to these two issues are all together different, so it’s important to note it up front!
Depth of Field
Just realize that sometimes the problem isn’t as much that you missed focus as it is you have a very shallow (sometimes it can be mere centimeters) depth of field.
This is especially true in times where you’re taking a pic of more than one person, where the person (etc) in the front is ‘in focus’ and person #2 is slightly behind, and thus ‘out of focus.’ Fixing this is an aperture issue.
Focus vs Sharpness
Focus and Sharpness are often terms (mistakenly) used interchangeably. But they’re different melons.
Sharpness is largely the result of the quality of your lens and the post production process. That said, you can always sharpen a well focused image in post production, even an image from a crappy lens. But you can never sharpen an out-of-focus image into focus. You just have a really sharp out-of-focus image.
The left side has slight sharpening applied. The right is SOOC. Can you tell? The eyes are the focal point, so look there. Granted, it’s not a huge difference because I prefer not to over-sharpen a pic such as this one (soft skin, wide open aperture).
Most images, especially if shot in RAW, need some sharpness applied in post-production. Granted, pics of your friends and faces generally don’t need as much sharpness in post as, say, a pic of a landscape, streetscape, flower, etc. Don’t worry, we cover it in the Post Production Module.
All to say, you might be in focus, you just need a little sharpness.
The Big 3 of AF
With those 2 disclaimers out of the way, let me say a quick word about the 3 largest factors that determine your AF success (or lack thereof). And btw AF stands for “Automatic Focus.”
- Light Level: To put it simply, the lower the level of light of your scene/subject, the harder it is for your AF to work well. Your AF absolutely needs light! And remember, what might not seem too dark to you is often a very low light situation for a camera (example, inside your living room at night with a few lamps on) might seem fine to you, but that’s really low light in ‘camera land.’
- Scene/Subject Contrast: Your AF essentially works by detecting lines of contrast. Try focusing on a blank wall, and your camera will search and search. Find where the trim meets that wall, and it’ll snap right into focus. More practically speaking, try to focus close up on a cheek and you might not get much luck. Focus where the eyelid meets the white of the eye, and bam…AF works in an instant. Just remember, AF systems need lines of contrast.
- Motion: The more motion, either of your subject or even you (your camera), the harder it will be for that AF to lock on.
Our game plan for nailing focus will thus hinge on the above 3 factors. That said, here’s a checklist approach to setting up your camera and technique that will nail your focus, every time.
The Focus Checklist
1. Use ONE Focal Point (or zone).
So here’s the thing, your camera most likely has multiple focal points. Some old DSLR’s have as few as 9, like this example:
Other cameras have hundreds of AF sensors, especially mirrorless cameras. Here’s an example of the AF sensor layout of a Sony a7 III, which features 693 AF points:
You can select whether all focus points are active at once, or if just one is active. And if just one is active, you get to select which one is active.
For cameras with hundreds of AF points, you can also select small “groups” or “zones” of AF points to be active.
The big point is this: when all of your focus points are active, you might think that’s advantageous. However, this is only the case in one main scenario: when you’re shooting fast moving action. In this case, having multiple sensors active can help the camera track the movement.
All other times (90% of the time for the average person reading this), I highly recommend just using ONE single focal point/sensor. Or at least a small grouping (if your camera allows for that).
Trust me, you’ll miss WAY less. Because now you know which focal sensor your camera is using (and thus you have more control).
With all of them active, you never know which one is going to find something to focus on. For example, you might want to focus on your friend 20 ft away on the right side of the frame, but with all the focal points/sensors active, on of them might catch something and lock onto it 60 ft away on the left side of the frame.
Check out this post for more on how multiple active focal points can lead to unfortunate misses.
When you know exactly which focal point/group/zone is active, you can be sure to put this ONE AF point over ‘the-thing-I-want-to-focus-on’ … which will help immensely.
Goal: Switch from having “All Focus Points” active to simply ONE focus point active. Or ONE group/zone active if your camera allow this.
2. DSLR Users: Make sure that focal point is a “cross-type” sensor.
If you shoot with a mirrorless camera, ignore this point. If you shoot with a DSLR, pay attention!
Let’s take point #1 above one step further, because not all focal sensors/points are created equal.
If you have a DSLR, your camera has a few types of AF sensors used for focusing. Here they are listed from best to worst in terms of performance / accuracy:
- Double Cross Type AF Sensors
- Cross Type AF Sensors
- Single Plane AF Sensors
Sparing the geeky talk, it all boils down to the fact that “cross-type” sensors are (at least) twice as good, because they detect contrast vertically and horizontally.
Those single plane sensors have failed me a dozen too many a time…. I only trust my cross-type sensors.
So how do you know which ones are “cross-type” and which ones aren’t? Well, of course your manual will tell you. You might also check your camera’s quick start guide, or even the sales page of your camera on a website.
One “for sure” answer: Just use your center point.
Yep, your center AF point is guaranteed to be the best possible sensor your camera makes. It’s hard to go wrong using this one. The only exception is when you’re shooting at extremely wide apertures in which your depth of field is mere inches or centimeters.
If you’re not shooting at, say f2.0 or bigger, no need to worry about it. Just use the center. If you find yourself shooting f2.0 or larger, don’t worry, we’ll cover your options further down in this lesson.
All said, take it from me, in any kind of low light, and sometimes even in pretty darn good light, those “single plane” sensors can be worthless. They often only perform decently in great light, with great lines of contrast. Using your “cross-type” sensor(s) are are drastically better. Like I said, that center focal sensor is a great place to land, and stay.
Goal: Make sure your center AF point is the ONE that is active. That’s the safest. Or if your camera is fancy, make sure that the ONE focal sensor you select is a “cross-type” sensor.
3. Use the correct AF Mode.
Okay…we’re getting closer to having our camera set up perfectly to nail focus. Last main step is to make sure you have the correct AF Mode selected.
Most DSLRs have a couple similar focus modes.
- “One Shot” / “Single Servo” Canon calls it “One Shot. Nikon calls it “Single Servo.” This mode is fine tuned for shooting stationary subjects. Even relatively stationary subjects (ie: people).
In One Shot mode, when you press the shutter button half way down, the AF Locks and you get a confirmation light in the lower display of your viewfinder (look for a green dot circle to appear). You can recompose anywhere, and the focus stays locked. It won’t move! Press the rest of the way down and the shutter clicks…pic complete. The shutter will not release if a focus lock isn’t obtained.
- “AI Servo” / “Continuous Servo” Canon calls it “AI Servo” and Nikon calls it “Continuous Servo.” This mode is made for moving subjects.
The camera hunts for a subject, but will not lock. In fact, once it finds a subject to grab onto, it will change continually to keep up with the subject but will never lock. You can snap the pic (release the shutter via full press) even if a focus isn’t attained.
- “AI Focus” … “Predictive Focus” … etc. Some cameras have more than the two AF Modes above. For example, Canon has an “AI Focus” mode that locks at first like “One Shot” mode, but then if the subject moves it will attempt to track it like the “continuous” mode. Kind of a hybrid, so to speak.
Personally, I’d stick with Single or Continuous.
Goal: Use “One Shot” / “Single” for stationary subjects. Use “Continuous” / “AI Servo” for moving subjects.
4. Focus on your subject.
Now that you have specific AF sensors activated and you have your AF Mode correctly set, you just need to hover that focal sensor/point over your subject, press the shutter release button halfway down, and your camera should snap into focus pronto.
You’ll also get a focus confirmation. It’s different with every camera, but usually you’ll see a green light at the bottom of your viewfinder and perhaps hear an audible “beep” once the focus locks. Sweet. You’ve acquired your focus!
Tip: In the case of photographing your family and friends (people photography), just keep in mind that the eye is the best place to focus on. For one, it has lines of contrast (a cheek doesn’t). For two, the eye is the portion of the face you most definitely want in focus during those times when there’s a very shallow depth of field.
This isn’t a great place to focus on (center point ONLY active), because there’s not much contrast on the skin, so it might just search and search. Technically, it’ll try and pic up whatever is in the circle, which could end up being the nostrils. We want the eyes.
This will work perfectly. Place the center AF point over the eye. It’s contrasty, so there’s plenty for the AF to “grip” or “lock” onto. Plus, it’s the eye, which is what we want to be in focus (most of the time).
5. Recompose and Fire
Now that your focus is set, keep your shutter button pressed halfway down and you’ll keep it locked. Now you’re free to recompose.
You can move the camera anywhere, even in the opposite direction. It’s still going to be locked at the same focal distance as when you pressed halfway down. After you’ve recomposed to the place that you want, just complete the pic by pressing the rest of the way down.
6. Be STILL.
When shooting close to your subject with very large apertures (2.8 and bigger), your depth of field can be mere inches (and at f1.2, even centimeters). If you move even a little (which is easier to do than you might think), you’re of course moving out of your locked focal plane.
Some would suggest using a tripod at this point. I can see their point, but I never use a tripod, and since you’re a normal teen trying to capture the life of your family and friends, you probably won’t either. So I won’t recommend it. Deal. Just realize the substitute is that you have to be still, including with your hands.
7. See clearly.
Your DSLR has a little wheel that will adjust your eyepiece (diopter). You can turn the wheel so that it adjusts to your vision. No, this won’t help your AF function any better. But it will help you function better. Which, I suppose in turn, does help everything else.
Use the diopter to adjust your eyepiece to your vision. It doesn’t help your AF work any better, but it helps you see what you’re doing, which is bound to help a little.
8. You always have manual.
If your scene is simply too dark or there’s not enough contrast for your AF to grab onto, there’s always manual. Flip the switch on your lens, and manually rotate the focus ring.
Your results will vary, because it might look in focus in your smallish viewfinder, but then be a bit off when you view the images large back on the computer. To this point, I highly recommend only using manual focus if your camera has “focus peaking.”
Focus peaking is a bit outside of the scope since manual focused won’t be used by most of our audience. But here’s a quick video covering it.
9. I’m still out of focus.
Bummer! Well, it could be your equipment.
There’s a old method that’s a relatively simple way to test your lens. You’ll need to gather your camera, lens that your having trouble with, a tripod, and a ruler. Simply lay the ruler on a table. Set up your camera ON the tripod (to take movement out of the equation) to where you’re looking at the ruler from roughly a 45 degree angle. Set up your camera AF as mentioned in the above steps. Place that Center AF point over the middle number of the ruler, focus, and take the shot (do NOT recompose). If the final image shows anything other than the middle number (your intended focal point), then your lens is basically mis-focusing and needs repair.
If that intended number is in focus, keep practicing your technique.
WHEW!! Time to Shoot
Let’s put your learning into practice.
- Use the steps above to shoot some pictures where you really nail the focus.
- Post your photos to our Member Chat (available only with the Photo Fix for Teens).