When I owned a photo-lab, a reoccurring question I heard from customers was, "Why are my pictures out of focus?" Of course, there are as many answers to that question as there are cameras and photographers.
Most modern cameras have an auto-focus feature that finds what it thinks is your subject and focuses the picture for you. But, like all mechanical things, sometimes the camera gets confused about what your subject really is, and focused on the background instead.
Cameras that focus on your subject's eyes?
As a fascinating side note, there is a new breed of cameras on the market that can actually find your subject's eyes (assuming your subject is a human or animal) and track those eyes as a point of focus.
Even if your subject is moving, like a flying bird, these amazing focus mechanisms can find and follow the birds eyes while in flight and keep the camera constantly focused. I have been a Canon guy for over 50 years, so this is a biased statement, but I believe there is no better focusing system on the market today than the ones in Canon's new "R series" mirrorless cameras. The $1,499 (as of June 2022) Canon R7 is one example.
There are times though when a photographer actually wants the background to be out of focus; I mean really out of focus. That is the subject of this post.
For example, the next time you search "bird photography" on the Internet, most of the photos you will see have one thing in common; the background is out of focus. The focus on the birds though is (hopefully) sharp and crisp. Below are a couple of bird examples I recently took.
So, what's going on here? How did I achieve this look and why?
I need to get a bit technical here, so stay with me. I think this concept of "depth-of-field" has incredible power to improve your own photographs.
What is depth of field and selective focus
When I was in photography school, we were taught a concept called "selective-focus." Said another way, a photographer has the ability to selectively choose what is in focus and what is not. Portrait photographers always master this skill. Clients do not want the background of a portrait to compete with their precious baby's face? That is one of the reasons that professional portrait studios use "old masters" backgrounds that appear out of focus behind the subject.
Furthermore, there are various kinds of out-of-focus backgrounds. Look behind the Mockingbird on the branch (above left) the background is filled with out-of-focus circles. Actually, those are called "circles of confusion" and the expensive lenses that create those circles are very sought-after by pro-photographers.
These "circles of confusion" match lighter areas in the background (in this case peaking through the branches and shadows). "Circles of confusion" often mean the photographer shot the photo with a long telephoto lens. I used a telephoto (200mm) lens on both birds above but the cardinal (right) has no circles of confusion. Why is that?
In the Cardinal photo, the background is also very much out of focus, but it is more creamy (sometimes called "bokeh") and it too is often sought after by pro-photographers. The difference — there are no circles of confusion because there are no smaller lighter areas like in the mockingbird photo.
With the Cardinal photo, the background is so totally out of focus that it turned creamy, like green butter. Again, I took this picture with a long telephoto lens (do you see a trend developing here about telephoto lenses and depth of field).
Below is a photo I look recently where the foreground and background are both in focus. This photo would not look normal if the grassy thistles and bird reflections were out of focus. So, as a photographer, foreground and background focus (or lack of it) can play to your benefit (or not).
How about the foreground focus?
I shot the photo below in my backyard and check out the foreground and background. Both are out of focus, but the robin is tack-sharp. This is a great example of "selective focus." The bird just literally pops off the page.
While were analyzing this photo, note also the direction of the light. It was low morning sun and it created nice textures in the leaves and the Robin's feathers. I say this to anyone who will listen; try to take advantage of early morning and late afternoon light. Both are good for almost any kind of photography. Noonday sun is normally your enemy.
Back to the topic of focus, the out-of-focus areas on the right side of the image are foreground leaves and the branches and the leaves behind the Robin are also out of focus. So, we can see here that there is a plane of focus (called "depth of field") is a few inches in front of the Robin and a few inches behind the Robin, and everything else is out of focus. This is technically called a "shallow depth of field" photo and is very desirable (as long as you keep your subject in focus). So, how can you achieve this look in your own pictures? I bet you thought we would never get there.
How to control depth of field
As a photographer, with almost any camera, there are several things you can do to control "depth-of-field."
Zoom-in with a telephoto lens. The longer the telephoto effect, usually the more shallow the depth of field.
Use a lower f-stop (wider open aperture). F/2.8 will create a more shallow depth-of-field than f/8. Shooting on "auto" will not allow you to do this, but many cameras have an automatic "portrait" mode. In this mode the camera tries to mimic this portrait look where the background is out of focus. It does this by cheating the settings to a faster shutter and more open aperture.
Lower the ISO to force the camera to use a more wide-open aperture. A lower ISO means less light, and less light tells the camera to do something to get the exposure right and that usually means slowing down the shutter or opening the aperture. By opening the aperture, you will create a more shallow depth of field.
Examples and camera settings
A preacher friend used to tell me that a good sermon has lots of illustrations. So, with that in mind, below are some illustrations of long depth-of-field versus shallow depth-field and what causes each one.
All of the below photos were taken on a tabletop. Lined up in front of the camera on the table are two objects, a taller carving and 2 feet in front of it is a shorter bowl. The camera lens is 9 feet from the taller object. The lens is a telephoto set at 135mm (medium telephoto). A pink Hydrangea plant is 6 feet behind the carving.
(photo left) was taken with the lens
f-stop set at f/2.8 (the aperture is wide open). Notice the shorter bowl in front of the taller carving is so out of focus it is almost indistinguishable. The pink Hydrangea plant is very out of focus too. This photo has what I would call a very shallow depth of field, with about a foot in front of the carving and a foot behind it, in-focus and it rapidly falls off after that.
But look what happens as I increase the f-stop below.
In this photo (right) all settings stay the same except the f-stop and I changed that to f/8. Now, the bowl in front is starting to take shape and the Hydrangea behind is more defined.
This photo (left) has all the same settings except the f-stop again and I changed that to f/11 (smaller aperture). Now the bowl is definitely coming into focus and you can tell the background is a pink Hydrangea.
On this photo (right) all the settings are the same except the aperture which I changed to f/32 (really small aperture).
Now the shorter bowl in front is definitely taking shape. It is not tack-sharp yet, but close. The Hydrangea is also looking more in focus.
The telephoto lens also compresses the photo. That is one of the ways you can always tell the photographer used a telephoto lens.
I used this demonstration to show the effect of just changing the f-stop on your camera. Remember, smaller f-stop means larger aperture (hole) size and more shallow depth of field. Larger f-stop means smaller aperture (hole) size and a much longer depth of field.
In summary, using your telephoto lens (or zooming to telephoto setting on a point and shoot camera) will create a shallow depth of field. Shooting with a wider aperture will do the same thing, or do both. But, what if I want more depth of field.
Shooting with a wide angle lens will almost guarantee everything will be in focus (longer depth of field). Cell phones have wide angle lenses built in. When shooting in bright light (like on a sunny beach) it is almost impossible to get a shallow depth of field because the camera wants to "stop-down" or make the aperture smaller (larger f-stop like f/22).
You could use a neutral density filter in front of the lens to compensate, but that would be way more technical than I am ready to get in this post.
When shooting with a cell phone, if you move really close to the object (example with a flower, getting a few inches away), you can make the background go out of focus.
Remember, when taking pictures, always look at your background before pressing the shutter. Make sure you do not have a telephone pole in the background that is growing out of the top of your favorite aunt's head. Look for distracting "photo-bombs" and shift your angle to suit.
I hope these tips will help you use depth of field and selective focus to your advantage to create better pictures.