To begin, we will need some simple supplies, most of which are easily obtainable in just about any stationary store or department store. Many of these items you may indeed have already sitting around in your home if you are the crafty type of person or have children in the home.
Of course, being a photography tutorial, you will need some type of camera to begin with, and for the best results, it should be a DSLR with a relatively fast lens. By fast, I'm talking about a lens that is capable of f/stops under f/4. I prefer using my Canon 50mm f/1.8 lens, as it's very inexpensive (under $125 USD new in box) and easy to obtain. If you don't have a Canon, don't worry...most camera manufacturers have an equivalent lens/s that are also inexpensive. I have not tried this technique on standard "point and shoot" compact cameras as of yet, and given the difference in technology and build of the lens', your results may vary greatly.
Items you will need
Camera : already discussed.
Construction Paper: Black, Heavy Grade, a few sheets will be enough.
Scissors : A sharp pair of standard scissors is adequate.
Tape: Any type of standard tape will do, if you want a more permanent device, black duct tape can also be used.
X-acto Knife or other precision cutting tool : this will be used to cut your shapes for the bokeh.
Small Ruler : For measuring
Pen/Pencil/Marker : For drawing shapes and templates
Time: This project, once the materials are gathered, should take approximately 15-25 minutes to complete.
Let us get started!
The first thing you want to do is to take one of your pieces of construction paper and cut a strip about 3-5 cm wide across the short side. Use your lens to measure the width as you want the strip wide enough to cover enough of the end of the lens to create a nice light-tight seal and stay attached, but, without covering the entire lens. we are merely making a 'cap' of sorts to sit on the end of the lens without compromising the lens controls (AF and IS buttons).
The length is not as important except that with wider lenses you want to ensure your strip is long enough to at least wrap upon itself by a few cm (at least an inch or so) to create a light-tight seal.
With your first strip cut out, take the lens and wrap the strip around the end and tape it in place. Again, making certain the strip is snug, but NOT taped or secured to the lens...we want to be able to gently slide it on/off when we need to.
Slide the base we just made off the end of the lens and set it to the side for now.
Place the lens face down on a piece of the construction paper and use the circumference (outside) of the lens to draw 2 circles around the lens onto the paper.
The first circle will be the actual width of the lens. The second circle will be 1.5-2 cm outside of the first circle (1/2 to 3/4 of an inch).
This is going to form the end of your cap.
When you are finished tracing your circles, proceed to cut them out along the lines of the outer (second) circle. As stated before, the circle you have just cut should be 1/2 inch or so LARGER than the lens or base you made.
You will need this extra space for the next step.
After your end cap is cut out, beginning from the outside of the circle, use your scissors to carefully cut notches up to, but NOT past the inner circle.
(If you cut past the inner circle, you will possibly introduce light leaks that will affect the finished image.)
After cutting all the way around the end cap, you will want to begin folding in the tabs inwards.
It is important to note, do this CAREFULLY, as you do not want to tear off any tabs or tear past the inner circle! If you do make a mistake, go back and redo the end-cap or again, you may introduce light-leaks that will affect the final image.
After all your tabs are bent inwards, take your scissors and cut out a slight rectangle from the center of your end-cap. Ensure you leave some room around the edges and on the top and bottom, as you are going to tape some retaining tabs on later to hold your Bokeh templates.
If the edges are too rough, you may trim these, as you don't want stray fibers continually falling onto the lens.
Now that your end-cap is cut out, the center trimmed and the tabs folded, it's time to pick up the base you made in the beginning and place the end-cap over the base. Begin taping the end-cap over the base. This is best accomplished by pre-cutting several pieces of tape (6-8) in approximately 1 inch (2.5 cm) lengths and having them ready for use, as you will be holding the cap and base with one hand and taping with the other. It's just easier that way.
Next, cut 2 small rectangular strips out, then tape them to the top and bottom of the rectangle you cut out earlier as seen in the diagram. These are going to be used as 'retaining clips' for the bokeh templates (to hold them in place while shooting).
Tape these along the top edges ONLY as you will need to be able to slide the templates under them in order to change the shape of the bokeh (as needed).
Now you need to cut out a few strips of paper that 'just' fit under the retaining tabs you taped to the end-cap. They should slide easily, but, also should be snug as to not create light-leaks.
Once you have a few strips cut, you can then measure and cut them to cover the rectangle (opening) in the end of the end-cap by a few mm in each direction. These will be used as your "templates" for creating your 'custom bokeh'.
Once everything is measured and in place, I recommend adding a bit more tape than you think is necessary...You don't want it falling apart in the middle of you project.
When you are finished with this step, you should have something like this...
Now that you have finished your end-cap, it's time to cut some custom templates. The shape of the desired bokeh is limited ONLY by your imagination and skill. Looking at the simple designs, you can pretty much cut any number of designs into the templates and the bokeh will take on the shape of the design.
When making your designs, I have found it best to keep the total size of the opening between 10-15mm. This may seem too small (it did to me at first), but, it seems to work best. Believe it or not, even when shooting, most of the image will be in focus (including the edges) with very little vignetting (dark edges) as long as you keep the template close to the face of the lens.
Also worthy of note, keep your edges trimmed. Stray fibers WILL show up in the final image in the bokeh. The finer the trim, the finer the image!
Finally slide the desired template onto the end-cap and place the end-cap over the lens...
And you are ready to shoot!
Bokeh is best shot with pin-point lighting in the back ground, for beginners wanting to give it a try, a string of cheap Christmas lights about 1 meter from the subject works very well.
Shoot in aperture priority mode if possible, at a very low f/stop, it will help blur the BG and bring out the bokeh. On and f/1.8 lens, I have found that f/2-3.5 works very well when you are fairly close to the subject.
If your camera is capable of "live-view" shooting, use it! you can preview the bokeh on the screen (YES, It actually works!). By previewing the shot, you can make adjustments before downloading the images and being disappointed. A bonus is if the camera has an "exposure preview" mode built in as well, you will be able to see in live time what the shot will look like before you shoot it.
After all your hard work, you will be able to obtain results like this...
The camera was set on a tripod about 1/2 meter from the flower and the flower was in a vase on a small table. I chose an outdoor daylight location since I wanted a natural looking shot instead of a studio type shot.
I used my newly created Custom Bokeh Kit with the heart template inserted and pre focused on the flower. Camera settings: ISO 100, 1/1000th, f/3.5, live-view activated and then composed the image.
Since it's essential to have good pin points of light in the background for the effect to work well, I chose to use a garden hose to spray some heavy water drops behind the flower, approximately 1/3-1/2 meter. The bright sunlight reflecting off these drops, along with the Heart in the lens created the image you see here. I was able to see and time the bokeh by using the live-view function on the back of the camera to make shooting the image even easier.
If you enjoy shooting indoors, or your subject is indoors. A very good alternate method is to use a string of Christmas light in the background, as these can be moved around and positioned to place the bokeh in any arrangement you need.