Like my previous article, this article is also partially inspired by some recent photography-oriented conversations I've had with my friend and mentor, ~Doomsday-Dawn.

Specifically, a topic that we've ended up discussing a couple of times is Depth of Field (commonly abbreviated as dof, DOF, or DoF). Depth of field refers, very generally, to how much of a photograph, from foreground to background, is in sharp focus. When you see a photograph with a very clear subject, and a fuzzy, out of focus background, this is an example of "depth of field effect."

Sometimes it can be confusing to talk about depth of field effects. I usually refer to "wide depth of field" if I'm talking about keeping most or all of a shot in sharp focus, or "narrow depth of field" if I'm talking about choosing to keep a significant portion of the frame out of focus.

How much depth of field, whether wide or narrow, is present in an image, corresponds to the aperture, or f-stop, that you set on your lens when shooting. Camera lenses have different ranges of apertures. Some have a wider range of f-stops available and some have a narrower range or even a fixed aperture. Thus, the particular lens that you're shooting with determines some things about what kind of depth of field effects you can achieve with it. The main principle to remember is that shooting with a large aperture (small f-stop number) results in narrow depth of field. Shooting with a small aperture (large f-stop number) results in wide depth of field.

When we start out as photographers, there is so much to learn about the basics of camera mechanics. The principles of setting a good exposure through ISO, shutter speed, and aperture, seem confusing at first. We're lucky to find a combination that works and gives us a proper exposure for a shot, much less to decide which of those factors is our priority, and successfully set the others around it! We might start out using "automatic mode" on the camera, and just letting the camera set everything for us.

Even if we're starting out using all manual settings, it's hard to understand the effects of all the settings at once. One of the first things we probably start to realize is that it's really difficult to take a clear photo at slow shutter speeds. So we begin to consciously "prioritize" our shutter speeds to something we know we can hold the camera steady at, and then set our aperture to whatever gives us a correct exposure at that shutter speed. Then we end up with however much depth of field effect happens to come about from using whatever that aperture setting turns out to be. Sometimes this works out great - and sometimes it ends up causing parts of the shot to be out of focus in disappointing ways.

(As an aside, most modern cameras have a "shutter priority" mode (often called 'TV' mode) and an "aperture priority" mode (often called 'AV' mode) that correspond to these choices - setting your exposure around a given shutter speed, or setting it around a given f-stop. So if you have these settings on your camera, and didn't understand what they mean or what they do for you, hopefully that is a little bit clearer now. While I'm primarily writing from the point of view of using manual selections for both shutter and aperture settings, there are some shooting situations where AV or TV mode are very useful!)

One of the things Adam and I have ended up talking about a couple of times now is that as we get more experienced as photographers, we start gaining a much better awareness about how depth of field affects the look of a photograph. Then we use that knowledge to choose how narrow or wide a depth of field we desire in a particular shot.

Some photos look great because they are sharp all the way from the close foreground to the far background. Everything is in finely focused detail. But other photos would not be nearly as effective if background details were in sharp focus. Those sharp background details might detract attention from the main subject, for example. Or, the blurring/out of focus effects of narrow depth of field might give a photo a mysterious or moody quality that would be lost if the whole frame were in perfectly sharp focus.

Since, once again, depth of field corresponds to the aperture or f-stop of the lens, we begin to pay more attention to "prioritizing" our exposures based around the aperture we want to shoot at. We're choosing our depth of field - whether wide or narrow - consciously - and then making our other camera settings work with our chosen aperture in order to set a correct exposure that will have the desired depth of field effect.

As you begin to be more aware of how wider and narrower depth of field effects impact a photo, you will start to have an idea of whether you want a wider or narrower depth of field for a particular image or shoot you are working on. You will start to consciously make DoF work for you!

In studio shoots, one of the most common ways to use a narrower DoF is to blur out a backdrop. Cloth studio backdrops often have wrinkles and dust or lint specks. If these are crystal clear and razor sharp in your image - they become something you wish you weren't able to see in the photo! Of course you can retouch them out. But, an even better option is to set up your depth of field so that your model or main subject is in sharp focus, and your backdrop is fuzzy and out of focus. Small wrinkles and specks will completely disappear into a nice soft and natural looking blur in your background, eliminating most, if not all, of the need to retouch spots of your background.

Narrow DoF can also be used to create mysterious abstract shots, or again, to draw more attention to the main subject of your photo, even if you can still see that there are other people or things in the background.

Some occasions where you might want a wide DoF - to keep everything in your frame sharp and clear - might be when you are shooting a group of people, or a complex scene. If you're shooting a group portrait, you probably want to make sure that the people in the back row are in equally clear focus as the people in the front row! Or if you are shooting a scene with a model in a set, you might want to show both the model in foreground to midground, and the set in midground to background, in sharp detail. Therefore, you would be setting your aperture to allow for a wide depth of field for those shots.

Keep in mind that the specific aperture needed for any particular desired amount of DoF effect depends greatly on how close you are to your subject while shooting, and how far your subject is from the background elements that you want to "blur" through DoF effect. Experience will start to give you a feel for what size of aperture you need to achieve a particular amount of DoF effect in your shot. It's much more important to understand the underlying principles than to try to "memorize" what f-stops to use for how much depth of field.

However, there are still some guiding principles to keep in mind. As mentioned earlier in this article, when you are using a wide aperture, this corresponds to a small f-stop number. Wide aperture/small f-stop number means you will get a much narrower DoF effect in your shot. For wider DoF and clarity across your whole frame, a smaller aperture, which corresponds to a larger f-stop number, does the trick!

Another factor to consider is how much light is present. When you're shooting in low light conditions where you don't have a flash or any other way to add more light, you will often end up shooting at a very wide aperture. This is because that wide aperture also lets much more light into your lens, to expose the photo correctly when there isn't as much light available. So if you take a lot of photos indoors without a flash, you might be noticing a lot of narrow DoF effects in your shots - a person in the foreground in clear focus, but everything else soft focused or outright blurry! You had to use that wide aperture/small f-stop number in order to get enough light into your camera for a good exposure, and this resulted in narrow depth of field.

When you're shooting with a small aperture for very wide depth of field and clarity across your whole frame, you are also allowing far less light into your lens for the camera to use for its exposure. This means there has to be a lot more and brighter light in the room/scene/etc in order for the camera to make a good exposure with that wide depth of field you want.

Now, when you're in the studio, one of the beautiful things is that you have control of how much light is present! Most studio strobes give you a range in power that equates to about five f-stops. The difference between the lowest power level of that strobe to the highest, or between aperture settings of five f-stops apart on your camera, is a very large difference in how much DoF effect you will have in the image!

So carrying through with what we've been discussing, if you know you are aiming for a narrower DoF to blur part of your subject and/or part of your backdrop, you'll need to start by setting a wide aperture on your lens. Then, adjust your light power to give a correct exposure at that aperture. If you are aiming for an image completely sharp and clear from foreground to background, you'll need to set a very small aperture on your lens, and power up your lights for a correct exposure at that small aperture. Again, it takes much more light power to get a correct exposure if you want wide depth of field - everything from front to back in sharp focus.

In a studio setting, you're usually shooting at the highest shutter speed available for syncing with your strobes. When you shoot with ambient/available/outdoor lighting, you have access to a much wider range of shutter speeds from your camera. This is good, because with ambient or available light, such as light coming in through a window, or sunlight outdoors, you can't conveniently change the power of your lights the way we just talked about. So, if you're selecting a desired aperture for your desired DoF effect, you can use a faster or slower shutter speed to let in more or less light. This becomes your primary means of balancing your exposure for the f-stop you are choosing to shoot at.

Briefly, faster shutter speeds let in less light - so if you want narrow depth of field, you're going to be using a wide aperture, which lets in a great deal of light. In bright sunlight, you might need to make your shutter speed much faster to avoid overexposing the shot. Or, if you're shooting for wide depth of field, you're going to be using a small aperture, and just like the previous example of shooting in a dim room indoors, you may need to move to a slower shutter speed to allow in enough light for a good exposure. It's always a balance, and not every option is available in every type of lighting condition.

One final note about shooting with a narrow depth of field concerns focal point. By definition, narrow depth of field means that part of your image is perfectly in focus, and other parts are not. If your DoF is extremely narrow, there might only be one small part of your frame that's sharply in focus. In order to make your shot look like you "meant" it to be that way, you have to be very aware of exactly where that "in focus" point of your frame is. Whether you're using a manual or autofocus camera, make sure you are adjusting your focus, or setting your autofocus point, to the specific part of the image that you want to be in sharp focus. Otherwise the depth of field will be more likely to work against you than for you, and your shot may miss the mark.

Commonly, when shooting a portrait of a person or animal, the most important point focal point might be the eye, or the face in general. When shooting nudes or figure work, DoF and selective focal point really change the effect of an image. A shot with the clearest focus on the model's navel gives a different mood than a shot with the clearest focus on the model's nipple! Neither is wrong, but the feel of the two shots, even though both are composed of a model with a bare torso, are very different! Regardless of where you may choose for it to be, the main point here is to choose your focal point by intention, and not at random.

Next time you're setting up a great shot, give a moment of thought to how depth of field could impact the photo you're about to take. It just might turn your image from a good shot, to a great one!


(A thank you to `TerrorCookie for some thoughtful and inquisitive comments and questions. Some of my replies to her comments are another part of what has gotten me thinking about the subjects of my last couple of photography articles!)