If you have watched a lot of photos of advanced photographers. You will have noticed that the backgrounds behind the subject regularly appear blurred. This ensures that in the subject is sent to your eye. And that there are no distracting elements, photos get a dreamy effect and more 3D.
With a simple setting on the aperture, you can also produce blurry backgrounds. The strength of the effect depends on the used lens. The distance from the subject to the background and the aperture used.
Blurry backgrounds are often used in portrait photography, photographing flowers and shooting products. The main goal is to make the background. And not to be distracted from the topic or extra to add mystery to the topic. In landscape photography it is mostly appreciated to have as much as possible sharpness of foreground to background. But deviate from this can produce an exciting effect.
A blurred background, combined with a bright light somewhere in the background. Gives a nice effect in the form of buttons that brighten the picture. You can also let rain disappear in the background.
Depth of Field
When shooting you have to deal with an invisible wall. The wall of the depth of field. Everything before and behind that wall is out of focus. The thickness of the wall ‘ – the sharp area – depends on the set aperture, the chosen focal length (number of mm). The distance to the subject and the sensor you are using (compact, crop SLR or 35 mm).
The point where you lay the focus is the most sharp. About 1/3rd in that point and 2/3rd after the point are also more or less sharp. The sharpness gradually decreases the further you get from the focus point. The combination of the aforementioned settings controls how fast the sharpness decreases.
Using a larger sensor makes it easier to get the background out of focus. One reason why many professional photographers choose a full – frame. In addition to better performance in dark conditions with high ISO values. But those cameras are a lot more expensive, more complicated to control and heavier.
You can also achieve the same effect by choosing somewhat more expensive lenses and/or to increase the distance between your subject and background. On the sensor you have little influence once you have the camera in your hands, that’s why I’ll not talk about that in the rest of the article.
Wide open aperture
The easiest way to get a blurred background is through your diaphragm to open it as far as possible. This can be done by your camera in the A or AV mode (depending on the brand is called aperture preferences otherwise) and the lowest possible number. The lower the number (f value), the larger the opening of the aperture and how fuzzier the background. Also the macro option (often identified by a flower icon) of your camera will open the aperture to achieve this effect.
Using a wider aperture – Canon EOS 5DmkII, at f/4, ISO 800
You will get the strongest effect, with a telephoto lens, for example on 200 or 300 mm, the elements in the photo are then pressed together, as it were, and the depth decreases much faster (causing the background to become out of focus) than for example, if you are shooting with a wide angle lens at 20 mm. How blurry the background gets, has to do with the focal length of the lens.
Distance From Your Subject
The last element is the distance from your subject to the background. Once the background falls outside the depth of field, it is out of focus, the further away the less detail there is. By putting your subject closer to the lens and further away from the background you bring them out of the sharpness area and you will get yourself a fuzzier background.
Please notice that as you get closer to your subject that also your composition changes. Make sure that you have all the elements that you want to include in the picture also in the new framework.
The best way to change depends on the depth of field, but just depends on the situation in which you are sitting. Sometimes you do not have the capability to get closer to your subject, or further from your background. Then there is no other choice than to switch your lens to more of a telephoto lens. If you do not get the desired effect with the maximum aperture opening, then you may need to move.
The strength of the effect depends on the maximum opening of your lens. With a maximum aperture of f/2 the effect stronger can be greater than with a maximum aperture of f/4, but this is also determined by the focal length. F/4 at 200 mm can have a fuzzier effect than f/2 on a 35 mm lens.
How far you can open the aperture, depends on the capabilities of your lens. In practice, there is almost always a direct relationship between the price of the lens and the maximum aperture opening. Many manufacturers are developing cheaper lenses that can open up to f/4 and a more professional line lenses whose aperture can be further opened.
If the maximum opening is larger than f/4 than you speak about a quick and bright lens.
More Expensive Variant
However, you do not always have to go for the more expensive variant of the lens. 50 mm and 85 mm lenses have often different variants in which a diaphragm aperture of f/1.8 often is quite affordable (such as the ‘ plastic fantastic ‘ 50 mm). Also have many macro lenses the ability to open and close the aperture and are also reasonably priced.
You might notice that all listed lenses are no zoom lenses. With a zoom lens, it is harder to get a wide open aperture to deliver over the full range of the zoom without a large and a heavy lens is (= expensive). Often you’ll see a combination of numbers, for example f/3.5-f/5.6. This means that the lens zoomed in the least f/3.5 maximum aperture and has fully zoomed in f/5.6 as maximum opening.
A telephoto lens is a popular way to get a blurred background, for a portrait photo this may give a negative effect (see later in this article). An alternative is to take a slightly shorter lens (short focal length) with a wider aperture (lower f number), for example an f/2.8 instead or an f/4 lens.
Often you come across this term in photography forums. With bokeh (say bokuh) means the quality of the background. One lens gives blurry backgrounds more pleasant than the other lens. If you are shooting with a lot of different lenses you will recognize this distinction eventually.
One lens produces a softer photo than the other lens. A nice bokeh is if you get a creamy effect from your lens.
Bokeh does not say anything about the depth of field, you cannot set more or less bokeh. It’s all about the quality of bokeh in the background.
Points Of Attention
The limited depth of field is the effect where we are looking for and this often produces nice pictures, but you must also be aware that there are also a number of disadvantages and concerns when shooting with a wide open aperture.
If you blur the background shapes in the background become simplified. This gives a calmer effect to the picture. Please note that there is no big lights or colors in the background that can distract the attention from the main subject. A small step to the left or right can completely change the background.
Blur Where You Need Sharpness
When you choose a wide open aperture than the area that is sharp will be paper thin. It is critical to focus on the correct point, so that the portion of the photo that you want to display is in really sharp focus. In the case of photographing a human or animal would you like to always have at least the nearest eye sharp. Put the focus just wrong, then you can screw up the picture.
On an LCD screen, even with 10 x reinforcement, it is often difficult to see if the critical part of the picture is really sharp. Are you not sure, then you might make a ladder with exposures of various aperture values and later on your computer screen chose the picture with the best depth of field.
More Expensive Lenses
Bright lenses are generally a lot more expensive and heavier than the cheaper less light sensitive variants. Camera manufacturers have the light sensitivity in the premium segment whereby the price is higher, but the product quality, used coatings to reduce flare and image quality is better. Earlier in the article I have named some lens varieties that you usually can purchase cheaper and yet get the desired effect.
Lenses Not At Their Sharpest
Lenses are not always equally focused over the entire range, each lens has an aperture area in which it can produce the best performance. This usually starts with 2 stops above the maximum opening. For example, an f/2.8 lens is only really sharp at f/5.6.
Now this should not stop you to choose the maximum opening, but sometimes you can still achieve a higher aperture value on a nice background and yet get a sharper result of your subject. Also the focusing can become less critical.
Chromatic aberration can be seen in the form of colored lines in areas of the picture where there is high contrast. For example, with tree branches against a fierce sky (because of the contrast difference often shown white on the picture) you’ll see purple, blue or yellow effects along the lines. A wide open aperture increases this risk.
Camera manufacturers have always gotten better at this in the coatings and shapes of lenses used. You can often reduce the effect also in post processing.
In The Studio Or On The Beach
Do you work with a studio flash then you have a new restriction in the form of the minimum shutter speed. Depending on the camera has been often 1/200-1/250s. When you shoot with a wide open aperture, then it could be that you need a faster shutter speed so the picture is not overexposed. By placing a neutral density filter (ND filter) in front of your lens, you can slow down the shutter speed, making it still possible yet with a wider aperture to photograph.
As you have seen in the above examples it shows that the use of a wide open aperture can give a separate effect to your photos. Large groups of photographers use this effect, shooting with a wide open aperture has become their style.
When I look at the pictures in my archive, I can see that it is almost certainly an addiction, but nowadays I try to discover the best setting for every situation. The effect by itself should not be the goal, but if it helps to tell your story, to captivate the viewer and to strengthen the end result, go for it!