| | | | | up a new world of things that happen too quickly |
| The lens aperture is a measure of how much light | | | | for the human eye to catch. |
| the lens will let through into the sensor in the | | | | As is now evident, the depth of field is directly |
| camera body. The bigger the aperture is, the | | | | related to the lens aperture. Having one of these |
| more light will shine through. Using a bigger | | | | ‘fast lenses’ on your D-SLR camera gives |
| aperture also results in less depth of field (depth | | | | you lot’s of creative possibilities. One of the |
| of focus, DOF). If it’s difficult for you to | | | | big challenges in serious photography is to |
| remember, just think of the small, pocket-sized | | | | separate your main subject from all the |
| digital cameras you can get nowadays. They tend | | | | background clutter, to focus the viewers attention |
| to render everything in focus opposed to the | | | | on the subject without distractions. To get a |
| more sturdy, professional single-lens-reflex (SLR) | | | | blurry background, set the aperture quite high, go |
| cameras that have the ability to create soft, | | | | a little close to your subject (without exaggerating |
| out-of-focus (OOF) areas behind the main subject. | | | | the perspective too much) and allow some |
| Big means plenty of light-sensitivity together with | | | | distance between your subject and the |
| a narrow focus area. | | | | background. It’s important to remember that |
| The aperture is measured in terms of f-stops and | | | | the placement of you, your subject and the |
| this can perhaps be a bit confusing since a smaller | | | | background also plays a role in how much |
| f-stop is equivalent to a larger aperture. It is | | | | blur-effect you get. It’s not only about what |
| usually written like this, the scale going from large | | | | lens aperture you are using. |
| aperture to small aperture:f/1.4, f/2, f/2.8, f/4, f | | | | Bokeh |
| 5.6, f/8, f/11, f/16... | | | | Ok, so now you have an out-of-focus |
| These are the standard values, separated by one | | | | background. But there’s a bit more to it than |
| unit called an f-stop. Each lens has a maximum | | | | that. (Admittedly, we are moving into the subtler |
| aperture and can be stopped down from there to | | | | details now.) If you look at the out-of-focus areas |
| gain larger depth of field and to set the exposure | | | | of different photos, you’ll see that it can look |
| (which it does together with the shutter and ISO | | | | quite different. Some lenses have a really nice, |
| speed). Another good reason to stop down your | | | | soft, smooth and silky way of rendering the |
| lens (to use a smaller aperture) is that the lens | | | | out-of-focus details while others have a tendency |
| usually works better when stopped down 2 to 4 | | | | to render hard rings and edges around |
| stops from it’s maximum value. It draws | | | | high-contrast objects. This can be a bit distracting |
| sharper and lessens unwanted effects such as | | | | to look at although it is somewhat subjective. The |
| chromatic aberration and vignetting. Using a lens | | | | quality of the out-of-focus areas is generally called |
| wide-open so to say, is rarely a good idea unless | | | | ‘bokeh’ and is largely decided by the way |
| you are pressed for light or using an absolute | | | | the lens is constructed, how many aperture |
| top-of-the-line lens. | | | | blades it has and what f-stop you are using. Photo |
| A fast lens, you say? | | | | aficionados can debate at length about the quality, |
| Sometimes the large-aperture lenses are also | | | | characteristics and effects the bokeh has on a |
| referred to by photographers as ‘fast | | | | photo while more ‘normal’ people would |
| lenses’. Strictly speaking this is nonsense since | | | | give far more importance to the focused areas |
| it’s still a piece of glass and not a racing car! | | | | of the photo. In some genres though, it does play |
| But what it means is that with a large aperture, | | | | a significant role. In portrait photography, wildlife |
| more light will come in allowing for a faster | | | | photography (using long tele-photo lenses) and |
| shutter time in the camera. The lens itself is in no | | | | macro photography the silky bokeh can really be |
| way ‘fast’, it’s just easier to say | | | | the dot that makes the ‘i’, an add a |
| that ‘the lens is fast’. | | | | magical touch that’s hard to pin down. |
| With a ‘fast lens’, you can use a high | | | | Try to incorporate some bokeh awareness into |
| shutter speed, ie. in the thousandths, 1/1000 sec | | | | your photography and there’s most likely |
| or less. This allows you to really capture moments | | | | improvements to me made. |
| that’s gone in the blink of an eye and opens | | | | |