4 Tips For Better Bokeh
Stick around photography for a while and you'll eventually hear the B word – bokeh. It's a classic camera snob term that enthusiasts use to blind beginners with science, but is actually quite a straightforward concept. Bokeh derives from the Japanese word boke, which means "blur" or "haze".
There is also the Japanese phrase boke-aji, or "blur quality." Put simply, bokeh refers to the blurred-out background you get when you take a portrait with a wide aperture selected on your lens. You can also get this effect if you take a portrait with a telephoto lens.
Whatever, it's a classic portrait technique, as you (usually) keep the main subject sharp while 'bokeh-ing' the background. As such, it's a great way of focussing attention on the main subject; it's attractive in its own right, and echoes how the human eye focuses on specific objects.
1) Understand how aperture works
Now, depending on your lens, the kind of bokeh you will get at f/1.4 is quite different to what you get at f/3.5. At a very wide aperture, pretty much all of the background is blurred out, and while you get a lot of the nice abstract shapes that bokeh fans love, you will also lose pretty much all background detail.
Narrowing the aperture (raising the f number) will also blur out the background while retaining some of the background information, which can be useful for adding context. It's a matter of choice; a food photographer might want to keep some blurred-out details of a kitchen or restaurant to add context, while a sports photographer might want to make a messy and distracting crowd or stadium as blurry as possible.
2) What if I don't have a very 'fast' lens
Don't worry if your lens only opens as wide as say, f/3.5. You can increase the distance between the background and your subject so bokeh even appears – even in images that are shot at narrower apertures like f/8. In effect you are decreasing the distance between the camera and the subject.
3) Watch the lighting
Lights and highly reflective objects create particularly nice bokeh. When they are out of focus, they go from being very bright, harsh-looking objects to softly diffused orbs. You can also get nice bokeh when highlights illuminate the background.
4) Choose your subject
As we have seen, bokeh effects work particularly well with portraits and macro photography, where you want to focus the attention on the main subject. It's not used so widely in conventional landscape photography, where you want the image to be in sharp focus from front to back (though there is always a time to break the rules).
Be aware too that when shooting at very wide apertures to get nice bokeh, sharpness will steadily fall away from the main point of focus – so even if a person's eyes are razor sharp you will struggle to keep their ears sharp, for example. Again, this might not be a problem depending on the purpose of the image. It's less of an issue on a romantic wedding shot than a passport or corporate photo!