Introduction: Bokeh Filter DIY

About: I like to play with toys and light

Bokeh (bo·keh \ˈbō-kā, -kə\ ) or the blurred quality/effect in the out of focus are of a photograph is not only fun to play with, but also easy to alter. Simply place a custom paper/carstock cutout (filter) in front of your lens and go shoot.

Step 1: Tools and Materials Needed

Assuming you have a camera with interchangeable lenses, you will need:

  • Fast Prime Lens
  • Compass, or Lens Cap
  • Ruler
  • Pencil/Marker
  • Black cardboard
  • Scalpel/ craft knife
  • Scissors
  • Cutting mat

Step 2: Determine Filter Size

Either measure the inner diameter of your lens or look on the inside of your lens cap for the the size and downsize 2-3 mm so the filter sits closer to the front element. You will have better results when your new filter is closer to your lens.

If you don’t like the metric system, I used 2.0 inches for 52 mm diameter lens & 3.0 inches for 72 mm

Step 3: Make a Filter Template

Using your compass, trace a circle sized for your lens and poke the compass through the paper in the center before removing it.This will make centering the cutout/design much easier. The tabs are optional and don’t need to be perfect, they just help in removing the filter.

If you don’t have a compass or you don’t want to measure, just trace your lens cap and cut on the inside of the line so the filter will fit closer to the lens.

Step 4: Determine Maximum Cutout Size

The table above has the maximum cutout sizes for a few lenses, you could also just try a size and see what happens or you could calculate the max size yourself:

We are making a new aperture for your lens, so we need to make the cutout smaller than the lens’ largest aperture. Since an f-stop is a ratio of focal length to the diameter of the aperture we simply divide the focal length of the lens by its widest aperture. For example a 50mm f/2 should have a cutout smaller than 50/2 or 25 mm (0.98 in)

Step 5: Trace Your New Filters

Use your new template to trace your filter blanks and add a little mark in the center of the circle (where you poked a hole with the compass). This will help you center your cutout.

Use your center mark and get creative drawing in different shapes. I like pencil for this, but for clarity I used a thick marker in the photos.

Step 6: Cut Out Filters

Now you are ready to cut out your shapes and filters. Start with the center design, this will give you more room to hold onto the card-stock while working with a knife. Then use scissors to cut out the circle and tabs.

Step 7: Camera Settings

Set your camera to Aperture Priority (A on Nikon, Av on Canon) and use your largest aperture (f/4 to f/1.2)

With smaller or complex designs:

  • Place camera on a tripod.
  • Prefocus on your subject.
  • Set camera to manual focus.
  • Place the filter in front of your lens.
  • Take photos.

Step 8: Notes

Some light meters and metering modes will not be accurate with small designs, so check your exposures and bracket as necessary.

Variables to play with:

  • Camera-subject-background distances
  • Angle of light source if using a reflective background (see photo of R2D2)
  • Cutout size
  • Aperture
Photography Contest 2017

Participated in the
Photography Contest 2017