It’s All About Focus

(Note:  This is lesson 6 on my “How It’s Done Series“)

I hope that you are finding my “How It’s Done” series of photography lessons useful.  By now, you might have noticed a theme flowing through all these various lessons.  I am trying to convey the importance of the photographer taking control of the picture making process.  Well, the most obvious thing a photographer can control is focus.  That’s what we’re going to cover in this lesson, focus.

From the previous lesson about depth of field you might have gleaned this important piece of information:  your camera can only focus at one specific distance at a time.  That’s a concept that a lot of beginner photographers have a hard time understanding.  It’s easy to get confused by multipoint auto focus.  When you are in multipoint auto focus mode your camera might show that you are focused on more than one point at a time.  Your camera isn’t lying to you.  It might have more than one point in acceptable focus, but that is only because all those points are pretty much in the same plane.  Your camera is only focused on one plain, one distance from the camera’s sensor.

Since you can only focus perfectly at one distance it is important that you make it count.  Take control of your focus.  My camera is almost never in multipoint mode.  In multipoint mode you have no idea what the camera is going to focus on.  I like to know exactly where I am focusing.  Put your camera in single point focus.  You’re going to have to check your owner’s manual for that.  And, as long as you are digging around in your manual, figure out how to toggle between the many different focus points that are available in single point focus.  If you plan to shoot any moving subjects, you’re going to need to be able to toggle your focus point without taking your eye away from the view finder.   For my canon 5D (via the custom functions menu) I was able to select the tiny joystick on the camera back as my focus point controller.  It works awesome.  I can set the focus point with my right thumb while keeping my eye to the view finder and my finger on the shutter button.  Your camera probably has its own slick way to select a focus point.  Dig around in the custom functions if you have to.  Total focus control is worth the small effort.

If you transitioned from consumer level camera up to a DSLR you might be surprised by how selective you can be with the focus control on your new DSLR.  With most point and shoot cameras the focus points are big old rectangles and you never really know precisely where the camera is focusing.   The focus point really doesn’t matter all that much with a small camera because the depth of field on point and shoot cameras is gigantic.  This deep depth of field is a result of the teeny tiny sensors used in consumer grade point and shoot cameras.  Small sensor size equals big depth of field, even with a big aperture — it’s a law of physics.  The larger sensor in your DSLR means you really have to know where you are focusing.  Improper focus is really easy to notice in photos taken with a DSLR.  The positive aspect of this precise focus control is you can be very creative with selective focus.  You can focus on your subject and then use of a wide aperture to blur the the background.  Conversly, if you want everything in the photo to be in focus (big depth of field) select a small aperture like f/16.  With a DSLR you get the best of both worlds.  However, to achieve successful results you have to know what you are doing.

You have to know exactly where you are focusing.  I mean exactly.  For example, when I take a picture of a person, I always focus on an eye.  Let me make that clear — I pick one eye, not both, to focus on.  Further more, if I am close enough to this person that I can make sure to focus on the pupil and not the eyelash, I’ll make sure the focus point is on the pupil only.  Does that sound like overkill?  Really it isn’t.  If you are shooting wide open, like f/2.8, it is immediately obvious in if the photographer accidentally focused on the tip of the nose rather than an eye.  You’ll see every pore and tiny hair on the nose and the subject’s eyes will be out of focus.  It’s distracting and looks terrible.  If a photographer does it right there is an opposite effect.  The eyes are sharp and nearly leap off the page.  The tip of the nose might be slightly out of focus because of the shallow depth of field, but no one notices.  The photo looks correct.

How do you get this exact focus?  There is a process.  It is really easy.  I’ll lay it out step by step.

Step 1 — Make sure your camera’s auto focus is turned on (did you think I’d recommend manual focus?  I’m not completely crazy)

Step 2 — Make sure you’re using only one focus point.  GET OUT OF MULTIPOINT MODE ALREADY!

Step 3 — Put your camera to your eye and compose the picture.

Step 4 — While keeping your camera to your eye, activate the focus point that is closest to the area you want in focus.  This focus point might not be over the area you want to focus on yet.  That’s OK.  You just want to be close.

Step 5 — Reposition your camera so that the active focus point is now directly over what you want to focus on.  If you’re photographing a person you would put the active focus point directly over one of your subject’s eyes.

Step 6 — Push your shutter button halfway down.  This engages the auto focus and, your camera should focus exactly on what the auto focus point is pointed at.

Step 7 — Keep the shutter button pressed halfway down.  This locks in the focus.  Now, recompose the picture the way you want.  Your focus remains the same as long as you don’t let up on the shutter button.

Step 8 — Push the shutter button all the way down to take your well focused picture.

I know that’s a lot of steps.  The process is actually easier to do than it is to explain.  Play around with your camera until you get really good at changing focus points.  Also, get a feel for how your shutter button works.  The halfway down press and focus method is absolutely key to taking good pictures.  I’d say it is the most important and basic tool I use.  If I’m hand holding the camera I use it on every single shot.

Now, we have to talk about when you’re auto focus doesn‘t work and how to make work again (I hate manual focusing and avoid it at all cost).

First, a bit of background.  Your auto focus works by maximizing contrast.  When you push the shutter button down the focus motor on the lens is engaged.  This motoring is called hunting.  The focus gets motored back and forth to find the sweet spot where the camera sees maximum contrast.  When the auto focus computer sees maximum contrast it stops the focus motor and the camera is now ready to take a picture.  A good camera and lens will focus quickly and you won’t even notice that the lens is hunting for the best contrast.   It looks as if the camera just magically knows how to pull a perfect focus.

What happens when the auto focus computer can’t find a best contrast?  The lens will hunt back and forth a couple times and sooner or later the camera gives up.  You see nothing but out of focus fuzz through the viewfinder.  The camera won’t take a picture.  If you want to see your camera’s auto focus fail, try this little experiment.  Point your camera at something blank and smooth — something like a white wall.  The wall can’t have any texture or this experiment won‘t work.  Now, try to get your camera to focus.  It won’t.  The lens will hunt back and forth but it will never find that sweet spot of maximum contrast.  It can’t because the blank white wall has no contrast.  Now, imagine if you stuck a piece of black tape on the wall.  Do you think your camera would focus when you aim the active focus point at the piece of tape?  Of course it would.  The black tape on white wall makes it easy for your camera to pick out maximum contrast.

Out in the real world there will be times when your camera won’t auto focus.  It happens for the same reason we discussed in the previous paragraph.  It can’t find a maximum contrast to lock onto.  This can happen when you’re shooting in low light.  It can happen when your shooting directly into bright sunlight, or it could happen while photographing a large smooth subject.  Fortunately there is an easy fix.  Simply find somewhere else to focus the camera.  Find an edge that has some contrast.  Or, maybe pick out a flaw, a crack, anything with some texture.  Just be careful to pick a spot that is near where you want your camera focused.  If you’re taking a picture of your black dog and your camera won’t focus on the dog, don’t focus on the tree that’s ten feet behind your dog.  Instead, try focusing on the grass directly below your dog.

Above is a photo that required some tricky focus maneuvers.  The primary subject, my sweet little woodland fairy, Ella, was backlit and standing in the shade.  The camera wouldn’t focus on her face, or even her dress.  Can you guess where I placed the auto focus point?  I put it the highlight in Ella’s hair.  The focus computer grabbed focus from there and keeping my finger lightly pressed down on the shutter button I recomposed the shot to the way you see it here.  The whole process took only a second or two.   You have to be well practiced if you want to pull this stuff off in a hurry.  Anyone who takes pictures of small children knows you’ve got to be quick.

Sometimes the light is so bad that your camera won’t focus even when pointed at a sharp, contrasty edge.  There is one more trick you can use.  Try switching to the center focus point.  Your camera’s center focus point usually can find focus better than any other single focus point.  On my ancient Canon 5D, I find myself using the center focus point quite often.  If you can’t pull a good focus using the center point, you can (as a last ditch effort) switch to multipoint and see if your camera picks up focus somewhere.  If that fails — you have to switch to manual focus.  Have fun with that.

Now that you know how to focus it’s time to think about where you want to focus.  It’s an important decision.  When someone looks at a photo their eye is pulled towards the sharpest, most focused area of the image.  The photographer has a certain amount of control over the viewer’s eye.  Think about where you want the viewer to look when you are choosing your point of focus.

Another consideration is what looks right.  With some types of photos there isn’t much choice where to focus.  If you don’t pick the right spot the photo looks all wrong.  People pictures are a good example.  If the eyes aren’t the center of focus the picture looks off.

The above photo is a good example of the type of photo that would look all wrong if you picked the wrong place to focus.  I focused on the horse closest to the camera.  I chose that horse because he was the most prominent.  Also, that horse was closest to the camera.  If I would have focused on either of the other horses the big guy up front would have looked a little blurry.  Most viewers don’t like foreground blur.  If I would have focused on the butte in the background the photo would have looked like an unfortunate accident.

When you’re a beginner it’s good practice to study other peoples photos.  Next time you pick up a magazine pay attention to where the photos are focused.  Pretty soon you’ll be able to pick out the center of focus without even thinking.  Make a mental note of what you like and don’t like.  Apply those techniques to your photos.

What if your trying to focus on a moving object?  No discussion of focus would be complete without covering servo mode.  Servo mode is available on pretty much every DSLR.  It’s a focus mode designed to track moving objects.  If you’re trying to photograph a race car, airshow aircraft, or Olympic sprinter, servo mode is your best friend.  It only works correctly when you are shooting bursts of pictures — holding the shutter button down.  What servo mode does is track a moving object and calculate its speed relative to the camera.  Then the real magic happens.  Servo mode knows the frame rate of your camera and it actually calculates the focus to stay slightly in front of the moving object so that the object is in correct focus at the exact fraction of a second the shutter is open.  The calculation only works if the object is moving at a constant speed, so don’t expect miracles.  However, you can expect some good results if you use servo mode correctly.

Above is a photo of my dog, Jack, shot in servo mode.  I had several considerations when planning this shot.  First of all, l I knew I’d need lots of light because this picture would require a fast shutter speed.   I had to wait for a sunny day to try this shot.  Secondly, from past experience with my camera I know that sometimes servo mode has a hard time tracking my black dog.  The solution — have Jack carry something bright and contrasty for the camera to focus on.  The last consideration is:  how far can I throw?  In order for servo mode to work correctly it has to be tracking an object that is moving at a fairly constant speed.  This means I have to start my burst of photos when Jack is going full speed straight towards me.  If I try to photograph him while he’s accelerating there’s a good chance servo mode won’t work.  It took a long toss and some luck to get this photo.

One more note on servo mode — it’s OK to use multipoint focus in servo mode.  The camera seems to do its best tracking while in multipoint mode.   The trade off is you don’t know exactly where the center of focus will be.  When I am shooting in servo mode I will often times use a smaller aperture than usual to ensure the entire subject falls within the depth of field.  This of course means a slower shutter speed unless you increase ISO.  Like everything in life there is always a tradeoff.

That’s pretty much everything I know about focusing a DSLR camera.  I hope it was helpful.  Please leave a comment if you have any questions.

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