The following guide was written by Christian Cable and presented at the 2013 Projects Night. You can download a PDF of Christian’s guide to creating your own custom bokeh lens hood for printing.
When you include out-of-focus points of light within your images you will know that they become colourful round blobs. (Often referred to as bokeh on the Internet). The shape of these blobs are dependent on the shape of the aperture within your lens that you shoot though.
However by shooting though an additional aperture which we can control the shape of, say a hole in some card, we can control the shape of these blobs for our own artistic purposes.
You will need
- A lens with a large aperture, ideally an f/1.4 or f/1.8.
- A piece of black card
- Some scissors (a craft knife is useful)
- A pencil
- A ruler
- Sticky tape or electrical tape
- Draw a circle on the card by tracing around the barrel of your lens. This circle will form the front of the lens hood.
- Draw a slightly larger circle around this. We’ll use this to create foldable flaps later on to help us attach the front to the barrel of the lens hood.
- Cut out the circle, and make some small cuts between the outer and inner circles to add foldable flaps.
- Draw and then cut out a small shape out of the middle of the circle. Make this around 1.5cm wide. Your aim here is to make your chosen shape smaller than the aperture you will be shooting through. Fun shapes to try are stars, love hearts, triangles and snowflakes. You might find this easier using a craft knife.
- Create the barrel of the lens hood by cutting out a long strip of card along the longest edge of your sheet of card. Aim for this to be around an inch wide.
- Wrap the strip of card loosely around the barrel of your lens and close this together with some sticky tape.
- Attach the front circle to the cardboard barrel and use the tape to cover any holes in the sides. It doesn’t have to be perfect just as long as you can easily place the hood over your lens.
- You should now have something which looks very much like the following picture. You’re all set!
How to use your bokeh lens hood
Set your lens on manual focus and defocus on a set of lights, something like fairy lights are ideal but other good subjects are cityscapes at night, Christmas trees or even the Blackpool Illuminations.
Use the widest aperture available and place the hood over your lens. You should now see that all the points of light in the scene take on the shape from your lens hood.
Beware that because you are shooting though an additional aperture you may need to adjust your exposure to let more light in.
Once you have a pleasing pattern of light you might want to experiment with using this as a background as in the following examples.