DSLRDIGITAL SINGLE LENS REFLEX
TYPES OF DIGITAL CAMERAS3 Main classifications
Point and Shoot Prosumer/hybrid Digital SLR
Point and Shoot digital Cameras (P&S)Commonly referred to as consumer digital cameras. Represent probably 90% of all digital cameras on the market Typically small, compact and lightweight Targeted at broad majority Typically very User-Friendly Image Quality has improved drastically
Hybrid Digital CamerasNot technically its own specification Common term used to describe advanced models of P&S(now also used to describe many entry level DSLR's) Similar in shape and appearance to Digital SLR's Typically have extended zoom range (812X Optical Equivalent) Typically combine user friendly P&S features with more advanced manual features.
Advantages and Disadvantages of P&S and hybrid models
Resolution Color space Aliasing Highlight disaster Delays
Wide-angle lenses Prints Battery drain Price
Digital SLR (DSLR)SLR Stands for Single Lens Reflex Have larger sensors, resulting in greater image quality Tend to favor manual control, lacking many automatic settings found on P&S Much larger and heavier Ability to interchange system lenses
(1)lens assembly (2)reflex mirror (3) focal-plane shutter (4)sensor
5)screen (6) condensing lens (7)pentaprism (8)eyepiece
Most of the entry level DSLRs use a pentamirror instead of the traditional pentaprism
DESIGN OF A DSLRWhen DSLR is not Capturing Image
The photographic lens located in front of the camera directs lights into the camera body. Light is then reflected by the mirror to the pentaprism and finally travels to the viewfinder where photographers can observe the scene. Notice that the mirror is flipped down and the shutter covers the image sensor from recording lights.
DESIGN OF A DSLRWhen Capturing an Image
The image capturing process starts when the shutter release button is pressed. Notice the mirror is flipped up from its original position, allowing light to travel to the sensor area. The shutter that covers the image sensor is now fully opened, and the image sensor is exposed under light and will be capturing the image.
The Image Sensor The Introduction
Image Sensor is the key device in DSLR, and serves the same function of capturing images as traditional films Image sensor is basically a silicon chip containing millions of light sensitive element called photosite, and is covered by a layer of color filter
The CCD Image Sensor invented in 1969 and introduced to the public in 1974. most common sensor used for TV cameras. When reading from such a sensor, the pixel values (charges) are transported across the sensor, line by line, and then shifted into an analog-to-digital converter, turning each pixel s value into a digital value two specific problems: > manufacturing Producing CCD sensors is very expensive, as special laboratories and machines are required to manufacture these sensors. >power drain CCD sensors also consume power at a rapid rate. Even though the CCD chips in consumerlevel cameras are only 1/3-inch across, they still drain power quickly.
The Image Sensor The Bayer LayerBayer Layer is a common type of color filter used in a DSLR. It refers to a specific arrangement for the red, blue, and green color filters. Bayer Layer contains twice as many green filters as blue and red to best simulate the human sight. It is because human eyes are most sensitive to green lights. Once the incoming light hits the Bayer Layer, each single color filter on the layer will allow one specific color to pass through to the image sensor.
The upper layer is the Bayer layer. The lower layer is the image sensor.
The Image Sensor The image capturing process
Once the light passes through the Bayer layer, the photosites located beneath will start recording the brightness of the light by accumulating a charge. The charge goes higher when the image sensor is exposed longer under lights. Each charge will become a single pixel after processing, and all pixels will finally form a digital image and be stored in the memory card for future reconstruction and editing.
The Image Sensor The sizeThere are two common sizes of image sensor used by DSLR. 135 size image sensor has a dimension of 36mm 24mm and is also called the full-frame sensor. APS-C size image sensor has a dimension of 22mm 15mm. The size of an image sensor has no effect on the size of the captured image, but affects the size of scene that will be captured.
This diagram illustrates the different sizes of scene that a full frame and an APS-C sensor are able to capture. The gray circle indicates the total view, or the field of view, of the camera.
The Image Sensor The sizeThe image displayed on the left illustrates a real example of the different fields of view that a full frame size sensor and an APS-C size sensor are able to capture. The image inside the box is equivalent to the scene captured by an APS-C sensor The overall image is equivalent to the scene captured by a full frame size sensor. Full frame size sensor has the advantage in wide-angle shooting. It is able to capture wider scene, and is often used for landscape photography. APS-C sensors capture narrower view, so objects in the image appear to be larger. It gives APS-C an advantage in long-distance shooting such as bird portraits because it is easier to emphasize on the photographed subject.
How the digital sensor works- Each digital image is made from millions of tiny squares, known as pixels.
- Essentially, an image is recorded by tiny microlenses (pixels) which make up the cameras sensor
Megapixels Determine the total size (Dimensions) of the recorded by camera - More MP does not always mean a better picture - Digital Image dimensions do not equal print dimensions
- For example a full quality image from an 8 megapixel camera will produce a digital image measuring approximately 9X14 inches but printing standards say that you should not print to Photo Quality any larger than 8X10
USE OF LENSES
COMPARISON OF USE OF ZOOM OPTION IN A DSLR