Photographers: how do i get a blurred backround with a focused object?

i have black and white photography, and i really need helpPhotographers: how do i get a blurred backround with a focused object?
The opening of the lens is called the aperture. The aperture size is controlled by the ';f-stop'; setting. The smaller the f-stop, the larger the aperture. The maximum aperture for a given lens might commonly be f/1.8, f/2.8, f/4, or something in that range.





Using a larger aperture will give you a shallower depth-of-field. Remember that you will need to adjust your shutter or film/sensor speed to compensate for the extra light the larger aperture is letting in.





Depth of field is also controlled by the length of the lens (telephotos give shallower DOF), the distance from the subject (closer gives shallower DOF), and the size of the sensor on a digicam (larger gives shallower DOF).





This online calculator may help:


http://www.dofmaster.com/dofjs.htmlPhotographers: how do i get a blurred backround with a focused object?
You need a lense with a large aperature, this is represented by the ';f/#'; a smaller number is a bigger aperature. also it helps to have you're subject closer to you than it is to the background. However if you have a picture already you can accomplish this in photoshop (it's rather advanced though and it looks fake in many instances)
simple, shortened answer: small f stop number
You need a lens that will give a large opening and you need to be able to control it. A large opening gives a shallow depth of field. You will then use the shutter speed to control the exposure, so it will be shorter. When you focus on the foreground, the background will blur out.


If you can't control lens opening on your camera, you can't do it, although you can with automatic shutter speed.
If you have a digital camera, there is usually a feature called ';macro';. That is what you want to use to get that kind of result.
It's quite difficult to do that on a point-and-shoot digital camera because the focal lengths are so small. On a DSLR, use the largest aperture you can, fill in the screen with your subject and keep your subject away from the background (you want the two to be at different distances, so you can focus on one and have the other one out of focus).





On a point-and-shoot digicam, if you use zoom and/or macro, you can sometimes get this effect.





I got this example of a macro shot that shows this effect well (though it's a tutorial on a different subject)
Go to expoimaging.net and order their ExpoAperture2 Depth of Field Calculator. You can read a review of it at shutterbug.com - just type expoaperture in the Search box.





This tool will help you fully understand Depth of Field.