On most of our portrait sessions I always get asked how I get the background to be so blurry. Most people think that it is some Photoshop trick that only pros know how to do. That is simply not the case. Anyone can purchase a 50mm F1.8 lens and get the same look. Lots of times I will use it so that the viewers attention is drawn to the subject I am photographing. Sometimes I use it because it is a pretty cool background. There are three major things to remember when using a camera. I am not talking about your point and shoot, although some have the options now too. I am referring to aperture, shutter speed, and ISO. Those three terms are the major terms when talking technically about a camera. Today I will tackle Aperture.
Aperture is the only term of the three that is referring to the lens only. The F after the focal length of the lens is the Aperture. The lower the number, the more light the lens brings in. So a 50mm F1.4 lens brings in more light than a 50mm F2.8 lens. The increase in light however makes the depth of field more shallow. In other words, as you open the aperture up you lose the amount of area that is in focus. For instance a F1.4 lens might only have 1 inch in focus, where as a F2.8 would have 4-5 inches in focus. These are not exact numbers, but guesses. But you should be able to get the picture. The lower the number the more the blades in the back of the camera are open. That's right your camera has blades, pretty cool. An easy way to get this affect on your camera is to put your camera on the A setting, not Auto. And then play around with the thumb or finger wheel on your camera. You should see a drastic difference in pictures. 50 F1.8 lenses are a cheap alternative for spending a ton of money on pro level lenses, while still getting a great low light lens. All of them, Nikon or Canon, can be purchased for less than $150.00. Great investment for you hobbyists.
The above image is shot at F1.4, see how the flowers get fuzzy as you move away from the area in focus. Thanks for reading, if you are looking to learn more stay tuned, I am going to try and do a few more posts about Technical info.