How to focus with a digital camera to make the background blurry?
Friday, February 4th, 2011 at
4:44 pm
I have noticed that some photographers are able to make the subject of their photographs sharp (like the persons face) and the background blurry using simple digital cameras which have a zoom lense. This makes the photographs look like they were taken by professionals whereas I know for a fact that all they are doing is using an autofocus camera. I don’t know how to do it though.
Anyone here have an idea how to do that?
Filed under: Digital Camera FAQ
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Thats called depth of field, otherwise known as DOF. You set the aperture.
it is called depth of field (DOF). it is done by selecting a small aperture on your camera. you cannot do this on an average point and shoot digital camera (where almost every setting is set automatically according to the subject’s surroundings). you must get a camera with a lens that lets you choose the aperture and shutter speed
“This makes the photographs look like they were taken by professionals”?
am i missing something? i though lighting was what made images look pro?
use a large aperture like F1.4 – f4, have the subject close to the camera and the BG far away
if you think auto will do it for you try the “portrait” mode
Wow. You are getting some misinformation here. Unreal. Ok, you use a LARGE aperture (Small F number) to reduce the area that is in sharp focus. In order to do this you need a fast lens, and the smaller the camera sensor, the faster the lens needs to be. This is why bokeh (the expression used to describe that “blurriness”) is so difficult to obtain with a P&S. On 1.5 crop camera you can get good bokeh at anywhere between F2: and F4: as a rule. Once you get up to F5.6 or more you start to lose it. On P&S with the usual very small sensor, you cannot really get a wide enough aperture to create a small depth of field.
The aperture, which basically is the hole where the light goes through the lens, is controlled by the camera, and can be overridden by you, the photographer. The bigger the hole, the “narrower” the amount of “in focus” the subject(s) will be.
Like this–focused on the metal gate, with different aperture settings, same place, on a tripod.
http://www.flickr.com/photos/little_pooky/2293925253/sizes/o/
This one shows the diff. between f 1.8 and f 5.6 http://www.flickr.com/photos/little_pooky/2265471299/
This is a practical use http://www.flickr.com/photos/little_pooky/3457895767/ Click on all sizes and “original” to see the original size (pretty big)
Hope this helps a bit. Probably a good idea to take a basic photography class, too. We all have to learn it the right way, as it is said that “trials and errors” is not a way to learn photography–I would like to add that when you grasp the basic understanding of photography, you’ll discover the joy of it.
Ever make a pinhole camera? Lots of people did as a child and even a lot of adults do.
A pinhole camera wroks because it has a real small hole.
A small hole keeps eveything in sharp focus. Modern cameras can use this feat of physics too.
The light coming into a pinhole can olnly come in through the little hole and onto the film, but ifthe hole was larger it can come in at all sorts of different angles– this is the blurry background you speak of
When the hole is large the actual focus plane is quite narrow, for example if someone took a picture of just a persons nose with a big hole the nose would be in focus, but everything in front of it and behind it wopuld be blurry. The ears of the person for example would be out of focus.
We use the large hole/small hole to give us differnt effects, just like the one you noticed in your question.
Of course we don’t call them big hole/small hole, we call them fstops.
fstops have numbers associated with them
F2 f2.8 f4 f5.6 f8 f11 f16 f22 and so on
To go from one number to the next lets in either half or double the light.
The big hole is f2 the smallest hole is f22 in my example. it uses a mathmatical formula so it is kind of confusing.
Now here is the deal, those numbers are used in every camera ever made, they are universal.
If I told somebody to shoot at a fstop of f2.8 they could use it no matter what camera they use ( there are exceptions but it’s not necessarly to discuss them here).
Everyone knows or should know that shooting at f 2.8 will give a blurry background. Same goes if someone was shooting at f22, everything would be in focus including the background.
Now there are other factors that need to be considered when taking a photograph like you shutter speed and ISO. Shutter speed is self explanatory and ISO is how sensitive the film or sensor is ti light.
All these factors are called stops. The aperture ( big hole/small hole ) is just one of them and it’s called fstop.
Well if you can’t manually set the aperture on the camera then it gets a little difficult. The portrait preset mode might help. If you really want to understand how this works you’ll have to read up on depth of field. A number of factors come into play, aperture, focal length (and the format of your film or sensor), distance from the camera (since you can only focus on a point, the focus drops of both to the front and behind that point). Having a basic understanding of how depth of field works means you’ll be able to choose exactly what area you want to focus.