Give your bokeh Christmas flair with this DIY lens filter

Feeling crafty? This easy lens modifier is a fun one for the holidays and only takes a few minutes to prepare. Bonus: Your kids will love it!

I love shooting wide open to capture beautiful bokeh behind my subject: The blurry, out of focus blobs that are characteristic of wide apertures. Bokeh take on the shape of the aperture, which is why high-end lenses are built with lots of curved diaphragm blades (the iris that lets light through the lens) to get the aperture as perfectly round as possible.

In this DIY, however, we’re going to deliberately change the aperture shape, thus sculpting the bokeh into fun holiday shapes! It’s kitsch but fun: In other words, perfect for Christmas. Don’t worry, this is a non-destructive craft: No modifications to the actual lens required, I promise.

How to create bokeh shapes with a wide aperture lens

You will need:

• A wide aperture lens of at least f/1.8, such as a nifty fifty (50mm f/1.8 lens). The 50mm f/1.8 will work well for this activity on both a full frame or a crop sensor camera. Whatever lens you choose, make sure it has at least 50mm for the focal length (longer would be even more effective).
• A step-up ring for your lens (a step-up ring is used to fit filters that are larger than the lens thread). The smaller diameter of the ring needs to match your lens thread diameter. If you can’t get a step-up ring, use Method 2 below instead.
• A sheet of thin (e.g. 2mm) black craft foam, the kind you would use for scrapbooking or card-making.
• Craft knife (e.g. an X-ACTO knife or similar).
• Scissors and a pen.

Optional extras and alternatives:

• If you can’t get craft foam or a step-up ring, an A4 sheet of black cardboard and sticky tape will work (see Method 2 below).
• Hole punches in different shapes, small amount of black cardboard, and glue (for Method 3).

Method 1: Shaping bokeh with craft foam and a step-up ring

This is the easiest method and takes only a few minutes. Here are the steps:

1. Trace the wider diameter of your step-up ring onto the craft foam.
2. Cut out the circle, on the inside of your traced line. Carefully trim the edges until the foam circle fits firmly inside the wider diameter of your step-up ring.
3. In the center of the foam circle, draw your shape (e.g. star, heart, etc.). It should be about 1 cm in size. Cut out the shape with the craft knife.
4. With the foam circle fitted in the wide diameter of the step-up ring, screw the ring onto the end of your lens. Your lens should now be covered with the black foam, with the shape cut-out in the middle.

Now you’re ready to shoot!

Method 2: Shaping bokeh with a cardboard cap

If you don’t have a step-up ring, this cardboard method works well:

1. Cut a strip of black cardboard about 5 cm wide from the long side of your A4 sheet.
2. Wrap the cardboard around your lens to make a tube. Tape it closed.
3. Slide the tube off the lens and trace the end to make a “lens diameter” circle on the remaining cardboard.
4. Draw (by hand) another circle around the traced one, about 1 cm (half an inch) bigger.
5. Cut out the bigger circle.
6. Snip the bigger circle at regular intervals, back to the “lens diameter” circle, to make tabs (see the diagram below: Cut the dotted lines).
7. Fold the tabs inwards so they sit at 90 degrees to the circle.
8. Draw and cut out your 1 cm shape, as in Method 1, in the middle of your circle.
9. Tape the circle to the end of the tube using the tabs.

To shoot, slide the tube onto your lens so that it’s capped by the cardboard circle.

Method 3: Making an interchangeable bokeh shaper

If you’re an advanced craftsgineer, you might like to try this method. Here, we make cardboard “slides” with different shaped holes, and a “bracket” on the circle to slip them in. I like this method because the hole punches give cleaner shapes than I can cut with the craft knife. Also, you only need to make one “cap” and can change the bokeh shape on the fly.

You can make this bracket on either the foam circle/step-up ring modifier (Method 1), or the cardboard cap (Method 2).

1. Make your cap as above, but instead of cutting a specific shape, cut a 1.5 cm square in the center.
2. Cut two 0.5 cm by 3 cm strips of cardboard or foam, and glue one on each side of the square cutout (as per the red rectangles in the diagram below), to make the “bracket.” Only put glue on the very ends of the strips (blue dots in the diagram).
3. Cut “slides” approx. 2 cm wide x 3 cm long.
4. Punch each slide with a different shape.
5. When glue is dry, push a slide under the bracket so that the punched shape of the slide is over the central square cut-out.

Now you are ready to shoot, and changing shapes is as easy as slipping one slide out and another in.

Next time I’ll share some tips and tricks for using your modifier. Until then, happy crafting!