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Living with Photography: Angling the Plane of Focus

By Norman Chan

When shooting at a fixed and relatively wide aperture, there are smarter things you can do with your composition that dramatically affect how a photo turns out.

The lure of bokeh in photography is strong. To the untrained eye, an out-of-focus background is correlated to a better photo, or at least the use of more expensive camera equipment, than a "flat" photo. That's why there's software to artificially add bokeh to photos by strategically blurring the background. And that's why many new photographers use wide-aperture lenses and shoot with the widest F-stop available to them. It's not something I recommend, but there's also technically nothing wrong with shooting wide open. You just have to know what you're getting into, and whether or now it's giving you the kind of photos you really want.

Photo credit: Flickr user janitors via Creative Commons.

Case in point, ever since getting the Canon 24-70mm f/2.8 zoom lens, I've shot the vast majority of my photos at the maximum aperture. A glance at my Lightroom Analytics from WonderCon, for example, shows that all but four of my photos were taken at f/2.8. Part of this is because I know what kind of depth-of-field that aperture gives me with a full-frame sensor, and part of it is because I'm not attuned to subtle DOF changes while in the moment, when I'm thinking about shifting ISO and shutter speeds. Optical viewfinders don't do a very good job approximating the depth-of-field of a resulting photo. I stick with f/2.8 for now while I try to master the camera's other attributes, and take advantage of the amount of light it gives me.

But when shooting at a fixed and relatively wide aperture, there are smarter things you can do with your composition that dramatically affect how a photo turns out. That's something I've recently become much more aware of; that while shooting, my brain tries to visualize the plane of focus where the parts of my subjects are sharp. And that by adjusting the camera angle and composition, I can manipulate that plane of focus to put more of the subject in focus without having to change the aperture.

The plane of focus (not to be confused with a camera's focal plane) is an imaginary two-dimensional plane that "slices" through your scene. Everything lying on that plane is in focus, and objects in front or in back of it are out of focus, to various degrees depending on the camera and optics. The plane lies parallel to the camera sensor, so as you tilt your camera, the plane moves along with it. For some of the photos below, I've Photoshopped an approximation of the plane of focus as it intersects with the subjects.

Let's take a look at this photo above, taken when we visited Frank Ippolito for the painting of the Zoidberg Project. As Frank was working, I was maneuvering around him snapping up photos of the painting process. I wanted to capture the detail not only of the paint job, but of the fine wrinkles and creases in the mask sculpt. So using auto-focus, I pinpointed the focus on Zoidberg's tentacles--the equivalent of his nose. And while I got those tentacles in focus, the result was an unflattering photo, because the rest of the mask was lost in the bokeh. When taking portraits, one of the most important parts of a subject to get in focus is their eyes--it's what viewers draw their own eyes toward--and focusing on the nose usually means losing focus on the eyes. And yes, while this Zoidberg mask didn't even technically have eyes yet, I wanted to find a way to get both his eye sockets and tentacles in focus at the same time. The solution was simple.

All I had to do was reposition the camera to a new perspective and angle, where I could imagine the plane of focus intersecting with more of the Zoidberg mask. The photo below shows the results of doing that. It's a portrait coming at Zoidberg from a different angle--aimed from higher up and tilted diagonally toward the eyes--but much more of the mask is in focus. You can clearly make out not only the wrinkles in the tentacles, but also those around the outside edge of the eye socket and even his lower lip.

This same technique applies to product or still life photography, which I would argue is even more difficult, or at least requires more decision-making. When not photographing faces, you don't have eyes as an easy go-to reference point for focus--you have to decide what it is about the object or product that you want viewers to draw their eyes toward, and how to position the object in such a way so that you get that focus without drowning the rest of the image out in bokeh.

The sample photo below, taken when I wrote about the HTC One's camera app (appropriately its "unfocus" feature), is an example of that bokeh drowning that I'm talking about. I angled the phone on the table so that the plane of focus--once again at f/2.8--would only slice through the screen where the app showed its "unfocus" button, since this is what I wanted readers to notice. That comes at the cost of the rest of the image looking blurred out, to a point that your brain takes a second to actually recognize where that plane of focus is at all. Something I could have done would be to put a secondary object to the right of the frame, also along the plane of focus, to help guide the mind in assessing where the focus points are in the photo.

In this second product shot, I was much more successful in using the plane of focus to guide the viewers to the salient and most interesting parts of the subject. Like eye contact in portrait photography, one thing that I am always aware of for product photography is whether or not I can get product names and logos in the plane of focus. For this Edgertronic high-speed camera, I knew that I wanted to get the name on the lower left of the device in focus, but also include other interesting visual elements in that plane of focus to balance out of the photo. That's why I angled the Edgertronic so that both the logo and some of the electronics (seen through the camera mount) would be in that plane. Another thing to note is that while finding that plane of focus using an optical viewfinder can be difficult (focus peaking in electronic viewfinders and LCDs make it much easier), shooting on patterned surfaces like a cutting mat helps tremendously.

I'll walk you through one final example, using a Sideshow Collectibles statue that I recently received--the Knifehead Kaiju from the movie Pacific Rim. I got this in the mail today and immediately wanted to snap some photos of it, which prompted me to think about planes of focus.

My first attempt at taking the photo emphasized two things--getting the eye of the statue in focus as well as keeping the entire horn in frame. It's not a bad photo, but when reviewing it, I decided that the horn was not the element of the subject I wanted to show off. In terms of the sculpt job, it's really the teeth of the statue that makes it menacing and gives the subject its character. Unfortunately, because of the awkward shape of Knifehead's head, a profile shot like the one below wasn't able to get the eye and teeth in plane of focus at the same time.

Because I had control of the lighting, the next thing I did was to lower the aperture, from f/2.8 all the way down to f/7.1. That's not exactly flattening the scene the way I would for a landscape shot, but it was definitely out of my normal portraiture range. And take a look below--even at f/7.1, I wasn't able to get the teeth in sharp focus along with the eye, while maintaining the same composition. There is only so much that shifting aperture can do. The plane of focus does not "widen" in absolute terms; it doesn't shift from a sliver to a fat block. Instead, the plane of focus is always a two-dimensional plane, and lowering the aperture changes the degrees of defocusing as you move away from that plane, whether in front of or behind it.

The solution meant some compromise--losing the tusk of Knifehead in my composition while I reframed and reangled to make the plane of focus intersect with the eyes and the teeth. Visualizing that plane in my head--remember, it's parallel to the camera sensor--informed me that I needed to come at the subject from below. Here's the shot that I ended up with, which includes the eye, teeth, and actually several more elements of Knifehead in the plane of focus.

And here's the photo again without any of the Photoshopped lines. Not bad, right?

Training your brain to visualize that plane of focus when you take photos will help you better compose your shots. I'm always asking myself a few questions: what is it about this subject that I want to get in focus? And when I get a core element (like eyes) in focus, how can I position the camera to add a secondary element to that plane of focus to balance out the photo? Adjusting focus isn't about one specific point in your frame--it's about how that one focus point relates to the other elements in the frame.

What are your own tricks for achieving focus and manipulating the plane of focus? Do you stick to a wide aperture or stop down to widen that plane? Leave your thoughts and tips in the comments below!