People often ask me how to create photos with those giant powdery blooms in the background. In many instances, these people will have already been told by another photographer “just use an f/1.4 lens” – but haven’t been able to figure it out. The truth is, using a really fast lens capable of f/2.8 or f/1.4 is only half the story.
The bloom that people talk about is basically a background that’s out of focus. Here’s an example I prepared comparing two photos taken from the same position with the same lens.
The amount of bloom you get depends on how far away the background is. The secret to taking advantage of it is understanding that you need to minimise the distance from the camera to the subject relative to the distance from the subject to the background. The lower the ratio, the greater the bloom.
I’ve prepared a little demonstration to show how this works. It involves myself, my children’s cubby house, and a camera. I’m using a Nikkor 85mm f/1.4G at f/1.4. The camera and the cubby house are both fixed in place – the only thing that’s moving is me.
The characteristics of that bloom (or “bokeh” to the pros and wannabes) is determined by what’s in the background and what’s in the lens itself. That is, the shape and arrangement of the glass, the number of blades in the aperture…
There’s no hard and fast rule on what makes good bokeh, but different lenses do have different characteristics. Here are a couple of examples I prepared earlier.
In the above example, the bloom doesn’t go overboard by blending the background into mush. It looks buttery-smooth, preserving enough of the colour and detail so that the subject is isolated without losing any of the context.
In this example, the lens is more reactive to light that’s out of focus, causing the lights from the street traffic to pop so brilliantly.
With this information in mind, it’s really not essential to use an expensive f/1.4 lens to create bloom in the background (although it does make the process a hell of a lot easier). Some simple techniques you can employ with any lens are:
- Pick a background that’s far away. For instance, point your lens down the street, instead of across it.
- Capture pops of colour by capturing strong contrasts of light, such as street lights by night or sunlight coming through foliage in the background.
- Set your aperture’s ‘f’ number as low as possible.
- Stand closer to your subject, and get your subject to stand further away from the background.
- Extend your focal length as far as possible. That is, zoom all the way out.
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