What Camera feature allows me to ajust the focus?

Question

I'm trying to find a camera that can take pictures that have a blurry background. i know this has to do with the focus, but what feature allows me to ajust the depth of field

Answer 1

Aperture priority.

Depth of Field is controlled by the width of your aperture diaphragm. Look for (A)perture or (M)anual.

The larger the film/sensor the "Tighter"/"Shallow" depth of field. The faster the lens the "Tighter"/"Shallow" the depth of field.

I think Dr. Sam is a God. What a great answer to this question!

Answer 2

It's going to be darn hard to "de-focus" too much using a digital camera while keeping the main subject in sharp focus. The smaller the sensor, the greater depth of field you will have. Generally speaking, the smaller the camera, the smaller the sensor. Most of the pictures you take with a digital camera are quite sharp from near to far distances and there is a reason for that which I will explain.

While we speak in terms of the 35 mm equivalency of digital lenses, don't forget that the digital sensors are usually smaller than a full-format 35 mm frame. Most of the more popular point and shoot cameras have the smaller sensors. It's only about 5 mm wide and 4 mm high. The 3X lens required to cover that angle of view is an ACTUAL 6-17 mm zoom lens. At these focal lengths, the background is going to almost always be in pretty sharp focus.

In other words, if you WANT to defocus the background, you are going to have to work pretty hard at it. You would have to zoom to the longer end of the lens and set the aperture open as wide as it will go, if your camera even allows you to control the aperture, and get pretty close to your main subject while having the background a fair distance away.

Put your subjects quite a distance in front of any background that will be visible in your photo. You could use a garden of flowers and stand your subjects 20 yards or so in front of them. Try the portrait mode to shift things towards a larger aperture, zoom the lens out all the way, and move YOURSELF backwards or forwards in order to frame the picture as you would like it. In summary, you want to use a longer telephoto length, position yourself as close as you can to the main subject to compose properly, and place the main subject as far from the background that you wish to have out of focus as you possibly can.

The bigger the sensor, the easier it will be to achieve pleasing bokeh. This means moving to a dSLR, which all have sensors about 20 times bigger than the typical P&S digicam. If you want to really go for brokeh (very bad pun intended), you can get a Canon 5D and you will get exactly the same effect you are accustomed to in a 35 mm camera, since the sensor is the same size as 35 mm film.

Here is an example with a point and shoot camera, although it does have the larger sensor (1/1.8") that makes it easier to blur the background. Even though this is macro mode and f/2.8, where the background should blur the most, it's not terribly blurry because it's relatively close to the subject.

http://www.flickr.com/photos/samfeinstein/872732755/

Here is an example with a point and shoot camera, so it CAN be done. The background is much farther away, though, and this is the larger sensor size.

http://www.flickr.com/photos/samfeinstein/843563558/

Compare that to this image, though, which has a similar subject-to-background distance. The SLR has the obvious advantage.

http://www.flickr.com/photos/samfeinstein/408446616/

Wikipedia does pretty well on the subject of depth of field. See: http://en.wikipedia.org/wiki/Depth_of_field

See also: http://www.photo.net/learn/optics/dofdigital/

See also: http://www.flickr.com/groups/dof/

MY DEMO ON FLICKR
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Go to this link and click on the first image, called "Fake Flowers 1." Then you can just click on each successive image in the set. You can read the comments to see what is going on and then you can just page through the demo left-to-right (1 to 5) and back again to compare the effects of the larger sensor or better lens.

http://www.flickr.com/photos/samfeinstein/sets/72157603455598439/

Answer 3

The aperture allows for a shallow or wide depth of field- aka how much is in focus. A smaller f-stop is a bigger opening for light to expose your image, allowing for a faster shutter speed, but sacrificing the amount of your subject that's in focus. You can do this either with Aperture priority (which allows the camera to determine the right shutter speed exposure) or manually (you have to set both aperture and shutter speed). Good luck.

Answer 4

Well, first you need a camera that has manual aperture settings.

If you have that, adjust that to get the depth of field you want.