Bokeh, that creamy out-of-focus area in photos, can be manipulated to achieve subtle and beautiful results. Today we’re going to show you how to turn some dirt cheap materials into a custom bokeh lens hood.
What Is This “Bokeh” Thing and What Does It Look Like?
Every photograph has what is known as a depth of field (or DOF). The depth of field, simply put, is the area of the photograph in focus. Everything too close to the the camera (and away focal point of the lens) is out of focus and anything too far away from the sweet spot is also out of focus. Any time you look at a portrait with a soft focused background or a nature photograph with a bird in flight against an unfocused background of trees, you’re seeing the effects of depth of field—only the object in the focal plane is in focus and everything closer or farther away than the focal plane is out of focus.
What we’re interested in is the too-far-away portion of the photo. The Japanese term for that area, and the most popularly used, is “bokeh” pronounced “boh-ka”. Old school American photographers will also refer to it as the “circle of confusion” or “blur circles” but bokeh better describes the concept we’re interested in for this tutorial as it goes beyond simply describing what is in and out of the focal area (as circle of confusion does) and refers instead to the entire area outside of the focus, the quality of the light, and the effects of the lens and lens aperture on the blur and highlight shapes within that out of focus area. In other words, bokeh is a word that completely encapsulates the essence and aesthetic quality of a blurred background photo. The photo above, by Kevin Dooley, does a great job of showcasing both depth of field and bokeh highlights.
On a naked camera lens, the shape of the blurry bokeh highlights is determined by the shape of the aperture blades–seen above–deep within the lens housing. Some companies produce camera apertures that create geometric and angular bokeh, some produce apertures that produce bokeh that is more circular. Portrait photographers often prize certain lenses for the subtle effect the aperture has on the background of their photos.
What we’re going to to do in this tutorial is create a lens hood for our camera lens that has a custom shape cut out of it. This custom cut-out will provide the shape of the bokeh, overriding the effects of lens aperture and allowing us to change the bokeh shape from a hexagonal or circular shape into anything our arts-and-crafts skill level will allow us to cut out of the template—radiation symbols, crescent moons, snow flakes, if you can find a craft hole-punch of it or carefully hand cut it out, you can turn it into a bokeh cap.
What Do I Need For This Tutorial?
For this tutorial you’ll need very few things, the camera equipment aside you can make it from scrap you find around the house. Here’s a run down of what you’ll need:
- A camera with a large aperture lens
- A few sheets of black card or cover stock
- A razor/craft knife
- A ruler/straight edge
- A pair of scissors
- A roll of dark tape (electrical tape works very well)
- Optional: A craft/scrapbooking hole punch
- Optional: A can roughly the diameter of your lens
- Optional: A cutting mat
For this tutorial we used a Nikon D80 camera with a Nikon 50mm 1.8 lens. The inexpensive 50mm 1.8 lenses you can get for most SLR cameras are excellent candidates for this project, the larger aperture lens you have access to the better. Also, of all the tools we used a humble soup can was the most useful one. We dug around in the pantry until we found a small can of condensed soup that was almost exactly the same size as the barrel of the 50mm lens. This made rolling/taping the lens hood so much easier as we could use the can as a sturdy mold to keep from crushing the hood as we worked with it.
Have your tools gathered up? Great! Let’s get started with a little DIY photography fun.
Crafting the Hood
Crafting the lens hood is a simple task—the most important part is that you take your time and measure carefully. Because this is a photography project taking the time to tape cleanly and seal off any light leaks is very important.
Although you can make this a fixed lens hood (i.e. the entire assembly only creates one bokeh shape) we opted to make our labor more worthwhile and craft an interchangeable model. Rather than make one disc and tape it down to the hood, we instead made a little view-finder like cutout (seen in the photo above) that allows us to slide individual bokeh templates in and out of the lens hood—thus you can use a snow flake for one photo and then slide it out and use a diamond shape for the next, only one lens hood required. We recommend this technique as it makes it way easier to use craft store paper punches. It’s much easier to fit a one inch wide strip of card stock into the paper punch than a three inch diameter disc. All that said, let’s get onto the actual steps.
First, grab a regular sheet of white computer paper or any other piece of scrap paper. Wrap it around your lens barrel and use a pen to mark off the diameter and the height of the lens. Unroll it and lay it on your cutting mat. Measure the height and diameter off the scrap paper and then transfer those measurements to the black card stock. Cut the barrel piece out. Wrap the cardstock around the barrel of the lens (or the same-sized can) and secure it with a small piece of tape. You want it snug but not so snug that it’s difficult to get on and off. After you’ve sized it, pull it off and wrap a piece of black tape all the way around the seam to hold it in place.
Next, we’ll need to cut the two cap pieces. This is where having a can that is the same size as the lens barrel is really helpful. If you have a can of the appropriate size, use that as a tracing template. If you don’t have a can of the appropriate size you can use a draftsman’s compass, carefully trace around the lens barrel and cut it to fit, or (if the cardstock is stiff enough) use the lens hood barrel you just made. However you arrive at a circular state of being, you’ll need to cut out two of them.
Once you have your two circles, grab your ruler. In the center of one of them draw a 1” square. Line up the two circles and carefully cut through them both with the razor knife. At this point you should have two cap pieces, roughly 3 inches or so in diameter (depending on the size of your lens) with a 1” square window cut into the center of them.
Using small strips of tape, affix the first cap pieces to the top of the cardstock barrel. For the first cap you want to tape all the way around and make sure you have a nice seal. Overlap the electrical tape slightly and press it down firmly.
For the second cap, place it over the first (make sure the squares are lined up) you need to leave a roughly 1.25” opening on opposite sides of the square. In the photo above the red arrows indicate the area that remains untaped. If you don’t leave the 1.25” gap on each side then you won’t be able to slide the bokeh templates in.
Now is a great time to reinforce the whole structure. If the hood isn’t already on the can, now is a great time to slide it on. Wrap the entire barrel with tape and double check that all the seams are sturdy and the tape is pressed down.
At this point all that is left to do is create the bokeh templates. Using the same card stock, cut a series of strips. Our strips were 3.25” long by 1.25” wide. 1.25” is a good width for the 1” window we cut in the caps, adjust the width to fit your lens—you want just enough overlap on each side of the barrel to make inserting and removing the slides easy.
Once you have a few strips cut you can start making your bokeh shapes. We had a small craft punch on hand which we used to punch out the star shape seen in the photo above. We also used a razor knife to cut out various other shapes including some smiley faces and a Christmas tree.
The big thing to keep in mind is that the cut out for the bokeh shouldn’t be too big or too small. If you make it too small you reduce the amount of light coming into the lens so much that the photo will be underexposed. If you make the cutout too big then the shape won’t be readily identifiable in the photo. An idea size if you’re using a 1.8 lens is around 15-20mm wide. If you’re using a lens with a higher aperture value like 3.5/f you might want to adjust your size accordingly. If you have to error in one direction, a little too big is preferable to a little too small as a blurrier bokeh highlight is more ideal than too little light getting into the camera.
Once you have a few shapes punched out it’s time to test the bokeh hood!
Bokeh Test Shots and Background Fun
Our first stop, thanks to the holiday season, was the living room. Christmas lights makes for great bokeh highlights. In the photo above we shot the Christmas tree with a naked lens and then again with the bokeh lens cap (and the star insert). In the first shot the highlights took on the shape of the lens aperture, a nearly perfectly round highlight. In the second shot the bokeh template overrules the shape of the lens aperture and the highlights take on the shape of the star cutout.
The most important thing is that you set your camera lens to the lowest aperture setting available. If it can only go down to 3.5, crank it down to 3.5. If it can go all the way to down to 1.4, crank it down to 1.4. The wider you can get your aperture the more pronounced your shapes will be. The tighter your aperture the less pronounced they’ll be—by the time you get up to the double digit aperture settings aperture numbers you’ll lose the highlight shapes all together.
Our Christmas tree cutout was a little on the small side and rather hard to cut out (who knew cutting a 14mm high Christmas tree into a sheet of cardstock with a razor knife would be so hard). None the less it demonstrates how whatever shape you cut into the slides, the shape will be influence the bokeh highlights.
Smiley faces were another easy to pull off bokeh option. By far the best looking one we had was the star, but that was due entirely to the crisp cut the craft punch made. If you’re into crafting or know an avid scrap booker you’ll have better access to a large number of craft punches. Another option would be to call local scrapbook stores and see if they have an in-house work area where they host scrap booking sessions and let customers try out materials. If so, you can pay them a visit and punch out a bunch of different templates.
Returning to the bokeh test: it’s all well and good to create fun abstract pictures of pretty lights but the real test is photographing people. We enlisted the help of our lovely and vivacious assistant, fired up the flash bulbs, and shot a few test shots. You’ll need to play with your exposure settings to get the subject in the foreground and the bokeh highlights in the background just the way you want them, but when you nail it the results are extremely pleasing. Who needs circles of light when you can have stars?
Before we leave the topic of custom bokeh hoods, it’s worth noting that there are commercial versions of the sweet DIY model we just made. When bokeh-altering first became popular in online photography communities it was all DIY, after a time, however, several companies released commercial bokeh kits.
The most economical and versatile on the market is the Bokeh Masters Kit. For $25 you get a holder, 21 shapes, 8 blanks, and a holder for all your bokeh altering gear. If you’re using the Lens Baby system, you can pick up a set of 9 bokeh discs for $20—not a bad price if you’re using the Lens Baby system but not very economical if you have to buy a $150+ Lens Baby lens to get started. For simple effects and the DIY pride, however, it’s tough to beat our tutorial—our total cash outlay was only a few bucks for a pack of heavy black card stock.
Jason Fitzpatrick is warranty-voiding DIYer and all around geek. When he's not documenting mods and hacks he's doing his best to make sure a generation of college students graduate knowing they should put their pants on one leg at a time and go on to greatness, just like Bruce Dickinson. You can follow him on Google+ if you'd like.
- Published 12/27/11