When we think of bracketing, most of us immediately think of exposure. All bracketing means is taking multiple shots with +/- adjustments. While I use exposure bracketing the most, I also bracket aperture quite often. Aperture is the opening and closing of the lens to determine how much light hits the sensor. It also controls your depth of field or how much of the image, from front to back, is in focus. Actually, I like to think about it a different way. Depth of field is how much of the image is out of focus. Why? Because often, when composing an image, it’s what is out of focus that matters most.
When considering the depth of field, take a look at what surrounds the focal point of your composition. Blur the background and foreground in your minds eye while determining how much blur you actually want. While this takes practice, it will be very beneficial.
This is where aperture bracketing comes into play. If you bracket your aperture settings, you can see on your LCD or on your computer at home, just how much blur you want to achieve the artistic vision you are seeking. Take the image of the tricycle below. I took this at a recycle dump. There was tons of clutter everywhere but I saw this sad, abandoned trike leaning against a dumpster.
I knew that a snapshot would look like I was at a dump taking a picture of trash. Full depth of field, or where everything is in focus, would not only be boring but really wouldn’t convey the sadness I found in the image. So, I knew I wanted to shoot at a very high aperture (lower number = larger opening in the lens). I was shooting with my Nikon 35mm f/1.4 prime which gives me the ability to achieve proper think depth of field.
When going for a shallow DOF, it’s very important to decide what will be the focal point of the image because most of the rest of the image will be defocused. Here, I bracketed my focus. I tried the wheel, the left side of the handle bars with the streamers, the right sided handle bars and finally, settled on the label on the front of the stem. I liked the handle bar on the left to be blurred against the blue of the dumpster and I thought having the dumpster blur from front to back gave the image some dimension. The stem was lined up with the rusted wheel which I liked and the shallow DOF also blurred the rubber falling off the front.
So, I bracketed the aperture to determine just how much blur I wanted. I tried shooting at f/8 (too much of everything), f/5.6 (better), f/2.8 (liking it) and f/1.4. What you see. Though this was handheld, it would have been better to have my tripod so I didn’t have to recompose every time I tried a different aperture. This shot took 10-12 snaps to get what I wanted. So, try bracketing your aperture to get the composition and depth you are envisioning.