Create your own bokeh shapes

Pooping reindeerPooping reindeer and a Baaah Humbug sheep – last year’s bad taste present!

Linking to Kat’s Creative Lights theme

One way to get creative with lights is to create your own bokeh shapes. ‘Bokeh’ is a Japanese term for the out-of-focus, blurred effect you get when you use a wide aperture on your lens.  If there are lights or bright highlights in the out-of-focus area then they normally show up as circular, or sometimes hexagonal, shapes.  However, you can turn bokeh into any shape you like with a simple trick.  All that’s needed is to make a black card mask with a shaped cutout in it that you then attach to the end of your lens.

This is what you do: place the end of your lens face down on some black card and draw a circle round it.  Cut out the circle.  Fold it in half and then in half again: where the fold lines cross is the exact centre of the circle and you need to make sure your cutout shape is centrally placed.  Using a craft knife, cut out the shape of your choice (maybe a star or a heart) so that it’s right in the centre and then fix the whole thing over the end of your lens with some sticky tape or masking tape. NPhoto Magazine has a little video on Youtube that gives nice clear instructions for a slightly more sophisticated version and should make it a bit clearer what you need to do – it’s always easier to show than to tell.

There are one or two things to keep in mind.  The size of your cutout shape must be smaller than the size of your aperture for it to work properly; if it isn’t, your whole picture will end up looking the same shape as the one you’ve cut out and it shouldn’t (what I mean by this is that you’ll end up with a heart-shaped picture, rather than just the bright spots being heart-shaped).

To figure out what size to make it, take the focal length of your lens and divide it by the size of the aperture.  So, a 50mm lens with an aperture setting of f2 would give a figure of 25mm and your shape would have to be smaller than this.  A 125mm lens with an aperture of f2.8 would give a figure of 44.5mm:

ie,  125÷ 2.8 = 44.5 (approximately)

A 75mm lens with an aperture of f4.5 would give a figure of 16.5mm (approximately):

ie, 75÷4.5 = 16.5

You can use a craft knife to cut your shape, or you could try using a shape punch if you want something more crisply cut or intricate.

You really need a fast lens for best results as the wider the available aperture, the easier it is to get this technique to work.  Ideally, you need to be able to get an aperture of f2.8 or wider.  If you prefer to buy a ready cut kit of bokeh shapes (see links at the end) then they will only work with apertures around this size or bigger.  I’ve tried using this technique with my zoom lens, which will only go down to f5.6 when it’s zoomed out, and it doesn’t work too well.

Because you’ve cut down the amount of light getting in, your exposure will be longer too, so you may need to use a tripod unless you’ve got some nice bright light around you.

Another problem that can arise is that your lens will probably rotate a bit as it focusses, so that your shape may end up not being upright.  You can avoid this by focussing before you attach it to the lens, using manual focus.

The fun bit lies in coming up with interesting shapes to try.  Hearts and stars are the obvious ones, but how about animals, umbrellas, cocktail glasses, mushrooms, butterflies, aeroplanes, arrows, snowflakes, bells, question marks, smiley faces, birds, lightning bolts, candles, bats, keyholes, flowers, musical notes or spirals?  Remember it’s the number of lights in the background that create the multiple shapes; you only have to cut one shape in your card.

Starry tree 2

This technique obviously lends itself to Christmas lights, but it can work well in other types of shots as well.  This rather lovely shot below, by J. Star from Flickr, has starry shaped bokeh in the background and shows a different way of using the effect.

Early in the morning

If you want to avoid the work of creating your own shapes, you can buy ready-made kits from The Bokeh Master.  Photojojo also do a Shaped Bokeh Kit that comes with 21 pre-cut shapes, a holster to attach them to your camera, and a pouch to keep them in.  Both sell for $25 and there might just be time to persuade someone to buy you one for Christmas…..

And if you want another really easy way to get this effect, treat yourself to a Lensbaby.  Not only is it a fun lens anyway, the aperture kit you get with the lens comes with  heart and star shaped aperture discs plus some blank ones from which you can cut your own shapes.  There’s also a separate Creative Aperture kit and you can find a gallery of photos using it on the Lensbaby site.  My own photos in this post were all taken with a Lensbaby, using the star shape.

I’d love to know how you get on with this if you decide to try it, particularly if you go down the DIY route!

Christmas glasses