Photography for the Web ppt

[...]... between them The number is not Photography for the Web (www.sitepoint.com) Photo Basics 31 an absolute measure of the aperture’s size, but is the related focal length of the lens; therefore, an aperture of any given f-stop will let in the same amount of light regardless of what lens you use The first slightly tricky point to remember about apertures is that the smaller the f-stop, the larger the aperture,... conditions Figure 1.8 The night sky shot at maximum sensor sensitivity Digital Images that Dazzle Get snapping today 8 Photography for the Web The Lens The first thing a person sees when you point a camera at them is the lens It’s more complex than it appears The piece of glass at the front of the camera is only the first of a series spread along the length of the lens tube There may be more than... create as close a match as possible for what the sensor sees through the main lens Because they’re a bit out of line Digital Images that Dazzle Get snapping today 16 Photography for the Web with the main lens, they don’t quite line up with the view; any markings that overlay the view are usually placed a little off center to compensate for the difference in alignment The Single Lens Reflex (SLR) camera... on the sensor, and the shutter closes again You’ve just taken a photo Behind the scenes there’s a bit more to do The processor takes the data from the sensor and applies whatever adjust­ ments are needed according to the scene mode, white balance, or other settings The data is then compressed and shifted to the memory card for storage If you have an SLR you’ll notice that the viewfinder goes black for. .. entering the camera, the shutter is the device that controls the amount of time the camera’s sensor is exposed to the light entering the camera When the shutter is closed, no light can reach the sensor Shutter speed is the measure of time the shutter is open A slow shutter speed means the shutter stays open for a long period of time, and, unsur­ prisingly, a fast shutter speed means the shutter is open for. .. turn on the display of the exposure meter) The exact look of the meter display varies from camera to camera, but the basic idea is represented in Figure 2.2 The indicator below the scale moves according to the current exposure settings and the amount of light falling on the sensor Figure 2.2 A typical in-camera exposure meter The meter measures the light reflected into the camera, compares it with the. .. the foreground and back­ ground To fill the frame of a wide-angle shot you need to be much closer to your subject, and this can cause considerable distortion If you use a 10mm lens to shoot a close-up of a person, it’s entirely possible for the tip of the nose to be twice as close to the camera as the person’s ears The sides of the head recede into the distance, while the nose looms larger in the foreground... aperture and a focus at infinity to capture the exploding fireworks Digital Images that Dazzle Get snapping today 22 Photography for the Web as trails of light The problem, of course, is that as well as recording the movement of the explo­ sions in the sky, it will equally capture any movement of the camera For shooting fireworks, a tripod or some other way of securing the camera to avoid vibration is essential... 16mm lens Notice how the left side of the face is smaller than the right, the nose is enormous, the top of the head seems to curve away from us, and the glasses lenses appear to be asymmetrical The lesson, I hope, is clear Avoid using a wide-angle lens to take portraits The Aperture and Shutter The aperture is the hole in a camera lens that allows light to enter the camera In among the many pieces of... than just the ratio of the maximum to the minimum magnification Lenses for SLR cameras are sold by their focal length The focal length of a lens is the distance from the optical center to the place where the light is fo­ cused—where the camera’s sensor is placed How to calculate or use that distance is less important than knowing how the focal length affects the view though the lens: a long focal length . possible for the tip of the nose to be twice as close to the camera as the person’s ears. The sides of the head recede into the distance, while the nose. megapixels on the smallest, as well as the largest, of these, but the picture quality difference is often visible. Photography for the Web (www.sitepoint.com)