Photography Q & A | Bokeh and the Magic Blur

A while back my wife asked me, "Why is it when I take a picture with my iPhone, my subject and the background is all in focus...but when you take a picture with your camera, your subject is in focus, but the background is blurred?" Good question.

The answer is your aperture or f/stop. Apertures or f/stops on all cameras control your focus depth. All cameras, be it smart phones, DSLR's and point 'n shoot cameras have f/stops. You can change it on most cameras, but on your iPhone you cannot. I’ll get into that later. If you're operating a camera where you can change the f/stop, you can use these settings as general guidelines: If I'm out and about shooting a landscape, with no general subject, I'll set my f/stop at f/11 or higher. Most of the time for capturing everything in focus, I'll even shoot at f/22. This will increase your depth of field and no part of the image will be blurred. If I'm shooting a portrait (where I want their face(s) in focus), I'll shoot at a lower f/stop to blur the background. Say f/2.8 or f/4 or higher. Make sense? No? Yeah, me neither. I'll give you a visual guide then.

Captured at f/5.6.

While this isn’t a spectacular photo by any means, the above shot was taken at f/5.6, and helps illustrate what I mean. Notice the background in relationship to the tree and the bird. The background is blurred a lot, while the tree and bird are in focus. Also, a portion of the branch (where the bird is sitting) is also in focus. Because, that portion of the tree is the same distance as the bird from the camera. Now, my focus points generally get targeted on eyes, especially in wildlife or portraits. However, when shooting around f/5.6, it will likely pull in immediate surrounding objects inside your focus. But as your eyes move away from your subject in the photo, you’ll see the focus starts to fall off. This effect is commonly known as 'bokeh.' I don't personally use that word, and even the correct pronunciation of it is often debated. Some people say, 'boke-ay' or 'boke-uh'. I even heard it once as 'boo-kay'. Who knows? You decide, then let me know. Or, better yet, don’t. I think I’m good with it.

Captured at F/22.

The image above with the golden dome was captured at f/22. See? Everything in that image is in focus and nothing is blurred.

Captured at f/1.8.

Now, here’s an extreme example of the ‘bokeh.’ The above image was captured at f/1.8. This is Maya, my Yellow Labrador. Also known as our backyard Decepticon. If you look at her eyes, they are sharp, but as you start to move away from her eyes, you start to see the focus fall off. Even parts of her eyelashes are not in focus. When shooting wide open, such as f/stops like f/1.4 or even f/2.8, you really have to be purposeful on where your focus points are. Minimal movement in the wrong direction can ruin your day pretty easily. Which is why, you typically wouldn’t use that low of an f/stop when shooting groups of people for portraits. The people on your focus points would probably be fine, but the ones on the outside (depending on how close you’re standing to them) would start to go blurry.

Quick tip on f/stops for people: As a general guideline, match the f/stop to the number of people in the photo, or go just slightly higher. So, if you’re taking a picture of a group of 4 people, if you stand back far enough, you’ll probably be fine at f/5.6 or a little higher. If you have more than that, such as 7-10 people, I’d go high to f/11 or a little higher.

So, how would you achieve ‘bokeh’ on your iPhone? Well, on some of the later model iPhones, the camera app itself has a mode called ‘Portrait’ mode. Simply use that mode when shooting instead of the regular mode. The only caveat I’d like to add is that most of the time, it works great. Sometimes, it doesn’t. If you look at the above photo, you’ll notice an area on the left side of her hair that was left out of the blurring algorithm. In this case, I think her cap and tassel confused the camera. But it does work well most of the time and can make your images look slightly more professional.

Full disclosure: I am by no means an expert on aperture. I just know what works for me. Another thing to keep in mind is when you open up your aperture, like when you choose a lower number, such as F/2.8, you're allowing more light to enter the lens for an exposure. When you close it down, like at F/22, you're allowing less light into the lens for an exposure. By doing this, you'll need to compensate by slowing or increasing your shutter speeds.

In any case, a wonderful photog friend of mine gave me this tip years ago when I was starting out: More F's means more in focus. Less F's means less in focus. So, the higher ‘F’ number, like say, F/22, the more ‘in focus’ your subject will be. The less ‘F’, such as F/5.6 or lower, the less your subject will be in focus. Clear as mud?

Awesome. Stay safe everyone.