The Purpose of Shallow Depth Of Field in Photography
Fun With Cameras XXXIII
Four photowalks. Four prompts. One experience.
I picked up my cameras for the last Fun With Cameras posts with simple but effective guidance that made me think about the quality of light, how I felt about a location at a specific hour of the day, and about how to capture all things round.
Today’s prompt sounds again simple: shallow depth of field.
Shallow Depth of Field Is Cool (until it isn’t)
And it can be: use a fast lens, ideally on the longer end of the spectrum, wide-open, reasonable distance between subject and background. Bum. Bokeh-galore.
But it shouldn’t be. That approach often results in a shallow depth of field that represents meaningless showing-off, the danger of the wonderful gift physics hands photographers. A shallow depth of field just because we can is never giving you meaningful results.
Even with a shorter lens, it’s far easier than you might believe to overdo the bokeh-trumps-everything move.
That’s why I rarely use my 35mm lens with apertures larger than 2.8. The resulting depth of field would be too short to render multiple subjects — whether it’s people or other objects — reasonably sharp unless they’re all the same (or similar) distance from the camera. Too little depth of field changes the image and might rob you of the point you’re trying to make.
Control over depth of field is just as important as composition, light, or moment. Used effectively, it can isolate and beautify the important elements of a scene.
It may also help to reduce the visual clutter you might not be able to eliminate otherwise.
But used without thought, it adds nothing at best and can distract at worst.
Late Winter to The Rescue
A sign that warns of the danger of drowning at the river Emscher begged to be used for this prompt.
The gas tower sits nicely in the background, soft but still recognizable.
Nevertheless, it doesn’t work for me. There’s no meaning for the soft gas tower in the background. There’s not enough river in the frame to inform us about the relevance of the sign (a compositional glitch, but still). Just because it can be done doesn’t mean one should blur the background without thought.
I have a few more pictures that I’m conflicted about, at best. But deciding the depth of field for an image, in general, should add subtle touches that help emphasize the core of a picture and build integral parts of a composition.
I enjoy the second and third pictures for that reason.
A late resurgence of winter temperatures handed me bonus motifs. I approached the scenes carefully. And the pictures I chose show the thin margins between making transitions into out-of-focus areas work and creating a difficult-to-read mess.
I enjoy the first. I’m not quite sure about the second. I’m pleased with how I used the light and how I placed the leaves. The green out-of-focus background looks smooth but competes a bit too strongly with the main subject.
The same holds for the final two images that show raindrops on grass leaves. The first is a bit too busy, and the background competes with the areas that are in focus. And while the second sample still has very similar colors for the fore- and background, I can live with how I used depth of field to let everything behind the drop slowly fade out of focus.
Think About Where You Want Depth Of Field
Throwing the foreground out of focus can easily be distracting. When I reached the canal the second morning, I found a scene where I wanted to play with it.
I started with the 35mm lens and moved to the 105mm later. The longer lens helped me create the balance I was looking for: the out-of-focus hedge in the front, the in-focus pipe installation (something to do with water, I think) in the middle layer, and the slightly soft canal in the background.
Now, why on Earth did I include that second picture?
I made that photograph because I was fascinated by the colorful sparkle I saw in the corner of my left eye when I worked on the gas tower picture with the cyclist passing on the path below.
I switched to the long lens and inspected the railing of a footbridge across the canal.
I don’t remember how close I was and if it was truly wide open. But to the best of my knowledge: what you see here is a macro lens (105 mm f 2.8), wide open (f 4.5 because macro lenses “slow down” as they get close to 1:1 magnification), close to its minimum focusing distance.
Depth of field can be calculated. With those parameters, the result is 0.16 cm or 1.6 mm (that’s 0.06 inches if that helps). In less mathematical terms: next to nothing.
I focused on the chip in the paint. Look closely, and you can see a thin ring of sharpness extending from that mark.
It doesn’t make any sense and is certainly a very extreme example. But wide apertures need a sharp mind and careful eye.
With all that being said, I enjoy this image as a very abstract one for the soft and golden shimmer.
Besides, experiments are the lifeblood of photographers. They don’t only provide a source of fascinating joy. They pave the path of education we’re all walking. Therefore, allowing yourself to make mistakes and analyze what didn’t work and why it didn’t work is a valuable part of the photographic experience.
Demo in the Forest
Depth of field is determined by focal length, distance to the subject, and aperture.
A 35mm lens is not a bokeh monster or cream machine, as some fast portrait lenses (think 85mm f 1.2 or 105mm 1.4 or 135mm 1.8) are sometimes called.
But a minimum focusing distance of 0.25 meters (0.85 feet) and an aperture of 1.8 can be used to great effect already.
The fourth picture from the top of this post is a 35mm picture at f 1.8, very close to that minimum focusing distance.
The pictures in this section are all 35mm pictures at f 1.8.
For the first two, I moved as close to the tree as I could to acquire focus. Notice that not even the entire trunk is in-focus. Also, note: I would have never clicked those frames had it not been for this post.
I do quite enjoy the third picture, though, for which I “approached the tree” as square on as I could. You could still argue, however, that more depth of field would be better.
In the final image, the wide aperture and close distance to the fence and other foreground clutter reduced its impact without eliminating it as context. Sometimes, that’s all you can do.
Final Isolation
These last three images weren’t part of my initial cull for this post. They don’t mean anything to me.
I had an idea for the round prompt with those pipes. But with the space available to me, I couldn’t make it work. The image above came the closest, but I couldn’t shake that one green crane in the background. And not the shallowest depth of field is beautifying that green blob. I could remove it in post-processing, of course, but that’s beside the point of what photography means to me.
I have a different image from the trailer handle sequence in last week’s post. I loved the light. But the background that the light dictated didn’t do it for me. Certainly not at f 8, but even f 1.8 doesn’t make it much better. Shallow depth of field is no magic wand.
It’s a compositional tool that can emphasize the point of a picture. It can tame a wild location. But that is not a given.
A combination of light and depth of field tames the location in the third picture (sort of). But it’s more the light than anything else that drew me to that trailer-locking device.
I hope you enjoyed today’s Fun With Cameras. I’ll share an athletic update tomorrow. Next week, I’ll have new reading recommendations and updates from A Journalist’s Diary.
