Bokeh Shapes

Bokeh is something that is talked about a lot within the photography community. For those of you who aren’t familiar with the word it comes from the Japanese word boke which means “blur.” It speaks to the quality of the light in the parts of the image that are out of focus. We typically find bokeh pleasing in portrait photography because it separates the subject from the background. But by understanding the physics of the camera we can make bokeh the subject of the photograph.

Pleasing bokeh is achieve by using a very wide aperture (low f-stop number) or by a long telephoto shot. Using a prime lens is a great way to achieve nice bokeh. But the quality of the bokeh can also depend on the mechanics of the lens. A single point of light will reveal the number of aperture blades in the lens. Higher quality lenses usually have more blades and thus result in a smoother bokeh. Lower quality lenses may result in pentagonal or hexagonal shapes because they may only have 5 or 6 blades.

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typical bokeh from a wide aperture lens

Now, if you want to take control of the shape of you bokeh you can artificially change the shape of the aperture which I’m going to talk about here. Here’s what you need to get started:

  • Prime lens (e.g. 50mm f/1.8)
  • x-acto knife
  • cardboard
  • single points of light

This is a great activity to do around the holidays because the Christmas lights are basically a multitude of individual points of light.

I’m sure you can buy kits online but I find that it’s pretty easy to make the cutouts. I’m using the 50mm lens mentioned above. You may need to tailor these instructions to other lenses. Use a nickle, penny or dime to draw a circle on the cardboard. You’ll want to make sure your shape is contained within that circle. This year I made a star and a smiley face.

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You’ll want to have nice clean edges which is why the x-acto knife is necessary. The cardboard needs to be stiff enough to hold it up in front of your lens. I’ve always gone with black but I would imagine any opaque paper board type material would work. Maybe next year I’ll try a 3-D printer!

Now, when you start taking your photos you’ll want to open your aperture as wide as it will go and set your focal distance. Remember the bokeh is the out of focus light so you need to be focusing on something closer than the lights. I would typically point my camera down and just focus on my feet before shooting. There are a lot of factors that play into the size and quality of the bokeh so play around with it. Some of the factors are the focal distance you pick and the distance to your subject (i.e. the lights).

Now that you’re all set hold the cardboard cutout up to your lens. If there’s light behind you then you’ll need to make sure you hold it tight to the lens so as not allow light to leak in. I’ve seen others make custom holders for their cards but I didn’t really find that totally necessary and that makes it much more complicated. All the photos on this post were achieved just by holding the card up to the lens.

As you look through the viewfinder you’ll see the effect of the shapes on the bokeh. You’ll also notice that shifting it slightly will impact the shapes too. If you want to introduce a subject into your shot you can focus on the subject and let the cutout impact the background lights.

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heart bokeh shape used in a portrait

The card obviously reduces the amount of light coming into the camera so you’ll have to take that into consideration. You may need to bump up the ISO higher than expected. You can also experience vignetting, again, since the cutout is reducing the actual open size of your lens.

That’s it. Give it a try and have fun. Since this technique doesn’t require exact focusing it can be even more enjoyable than regular shooting in low light situations. My family and I always visit the Blossom of Lights at the Denver Botanic Gardens and the kids get these fun glasses that make the lights look like snow flakes or ginger bread men. They get the glasses and bring my cards and we all have a great time.

Check out these photos from our 2018 visit to the Blossom of Lights