Tutorial: How do I take photos with blurred backgrounds?
I am writing this one for my friends who just got their first camera (usually a DSLR) and who often ask me one basic question – just how do you get to take photos with blurry backgrounds? Photo buffs beware, there is not much in this article for you. There are plenty of resources on the web where this theme is discussed in detail that would satisfy a more advanced user but here I just want to answer this question simply, or as simply as possible as far as I can.
First of all, I had this exact same problem, the first ‘proper’ camera that I got was a Canon 350d which came in a package with a small kit zoom lens (if remember correctly it was 18-50mm). I got home and hurriedly charged my battery, went out and started shooting. Try as I might I could never produce the magical background blur I was after. I tried changing shooting mode on my camera from landscape to portrait to fully manual but nothing helped. Every picture I took was sharp and if there was some background blur it was slight. Just how do the other people on Flickr get those creamy, soft blurs it was beyond me. So I returned my camera after a couple of weeks thinking that I need a more expensive DSLR to get what I want. I let the issue rest for a year or two before I got the tickle again.
So what’s the catch – will a more expensive DSLR get you to the end goal? The answer is a little more complicated then a simple yes or no as the problem is predominantly not with the camera but with your lens. In essence the blurring of the background is not an effect that lens produces it is a consequence of the technical limits of a lens to see wide range of distances in sharp focus under certain conditions. You might say that the lens then behaves as if it were shortsighted. This technical limitation has been put into good use by photographers who mainly use it to remove distracting backgrounds, to accentuate the subject and throw the rest of the ‘junk’ in scene out of focus.
There are four factors that contribute to increasing the ability of your gear to take photos with soft background blur. These are:
- the aperture of your lens
- the focal length of your lens
- camera, subject, background distance
- your DSLR’s sensor size
Let’s cover these in more detail but let me tell you immediately that the last point (sensor size) is the least important for you now. It seems like the trick is in the lens and in the way you compose your scene.
I am not going to go on about this ad nauseam so let me tell you this much – aperture value tells you how much light the lens is able to gather. It gathers more light by opening the blades inside the lens more. You can tell what the aperture range of your lens is by looking at numbers on your lens marked with a letter f. For instance, f2,8 or f/3.5 or f/3.5-5.6. The lower the f number the more light the lens lets in and the chances of getting soft backgrounds increase. Lenses with f value 2.8 or below are called fast lenses or low light lenses and they are the ones you want. Fast lenses’ primary goal is to let you shoot with less light, the blurring of the out of focus areas you want is a consequence of technical limitations of the lens at wide apertures (small f numbers). The wider the aperture (the smaller the f number) the bigger the hole in your bank account will be. You pay for the speed or the ability to shoot in less light then normal.
In order to tell the camera what aperture value to use you need to get into the camera aperture priority mode (usually marked as A). You will then be able to select the aperture value and the camera will automatically adjust other parameters such as shutter speed.
Above f2.8 things start to be more and more in focus and the background blur you get starts to be busier, less creamy. There is a way to compensate for this with focal lenght – keep reading on.
To put it simply this is the field of view of your lens. The values are expressed in millimetres. The smaller the value the more wide angle the lens is (you see more), the higher the value and the lens becomes a zoom. If you had a 200mm lens then you would see far with it, like using binoculars. You probably have a lens that covers a range say, 18-200mm. This means you get to take wide angle as well as zoom far into the distance.
How does this affect background blur? Again the simple rule is that higher the zoom (higher the mm number) the more blurred the background will be. If you have a slow lens with f value say f5 but one that can also zoom to say 100mm plus, then you should get the blurring effect. Try it, take a close up portrait at say 35mm and f value of f5 and then back off and take the same shot with 100mm at f5 and you will see a difference.
Camera, Subject, Background Distance
Before you go off to try the portrait shot as outlined above you need to know one more thing. The closer you get the subject to your camera and the further the background behind your subject is the more chance you will have to achieve background blur. If you take a portrait or a person standing closely in front of a wall you will get less background blur then if that wall was 10m behind them and they were close to you.
Argh… this sounds very complicated… OK.. buy a lens with aperture f value of 2.8 or below and with focal length that covers 50mm and/or above and you will be capable of taking softer background blurs. The only other thing to keep in mind is that it also helps if there you keep your subject as close as possible to your lens and keep as big a distance between subject and background as possible. Hope this is simple enough.
I also mentioned sensor size as one of four factors in this story of background blur. This is not something you should put too much emphasis on but a full frame sensor will get you nicer, softer background blur. I am not going to go into why (we said we’ll keep it simple), I will just tell you that this is a subtler point. Get the right lens and get the right subject-background distance and you will get there.
There are many camera brands out there at the moment so let me be a little conservative and only cover three examples. The recommended lenses here are cheap, entry level lenses that will give you the ability to take photos with soft background blur for as little money as possible. All three lenses are prime lenses, as in you cannot zoom with them but have a constant angle of view.
- Canon EF 50mm f1.8 (GBP89) – this is a Canon that gives you f1.8 for next to no money. Portraits will look really nice with this lens.
- Nikon 50mm f1.8 D AF (GBP110) – Nikon’s version of a fast prime lens. Slightly more expensive then Canon’s version but that is the main difference.
- Four thirds lens (Olympus, Panasonic, SIGMA), Panasonic 20mm f1.7 Lumix G (GBP300) – The difference in f value between Nikon and Canon’s recommended lenses will not give you any real world difference in amount of blur. This lens costs considerably more because it is tiny and is therefore probably costlier to make.
If you remember I told you before that the ability of the lens to keep out of focus areas in soft blur is not an effect but a consequence of technical limitation of the lens. When you shoot at say f1.8 then the quality of in-focus area of the image will be lower then at f8. Things in focus will look relatively sharp as the out of focus parts of the image will be very blurry but images shot with wide aperture (small f numbers) suffer from many problems such as softness, low contrast, flare… On top of that you will have to be very precise with your focusing as only the things in absolute focus will look sharp and everything outside it will gradually be blurred away.
What is the best lens for best background blur? Arguably it is Leica’s Noctilux 50mm f0.95 ASPH. It is manual focus only and it costs a cool $10,000. Even this bank breaking lens still has the same performance issues I outlined above but to a smaller degree. I told you that the faster you go the more you pay. I meant it.
That’s it. This is the simple story, simple word of advice. In this article I told you how to get the background blur effect. If you want to know the answer as to why background blur occurs then read on to my next article on this subject.
February 7, 2010