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Digital Single-Lens Reflex Camera

Digital Single-Lens Reflex Camera

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Digital Single-Lens Reflex Camera

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  1. Digital Single-Lens Reflex Camera Peter Hsieh Writing 2E

  2. Introduction • Digital Single-lens Reflex Camera, or DSLR, is a type of digital camera that provides the capability of interchanging lenses and wider photo-shooting options than normal consumer cameras. • It serves the purpose of capturing images in digital format • A DSLR contains a photographic lens, a viewfinder, a shutter, and an image sensor.

  3. Design of a DSLR When 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. Diagram originally from www.yesmag.bc.ca, modified by Peter Hsieh

  4. Design of a DSLR 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. When Capturing an Image Diagram originally from www.yesmag.bc.ca, modified by Peter Hsieh

  5. Specific Part 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 Howstuffwork: How Digital Camera Work http://electronics.howstuffworks.com/digital-camera2.htm

  6. Specific Part The Image Sensor – The Bayer Layer • Bayer 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. http://en.wikipedia.org/wiki/Bayer_filter

  7. Specific Part 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. http://en.wikipedia.org/wiki/Bayer_filter

  8. Specific Part The Image Sensor – The size • There 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. http://en.wikipedia.org/wiki/Bayer_filter

  9. Specific Part The Image Sensor – The size • The 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. http://en.wikipedia.org/wiki/Bayer_filter

  10. Specific Part • Every digital photograph is a combination of millions of pixel. Each pixel is produced by a single photosite on the image sensor so that each photograph will have a number of pixels equivalent to the number of photosites. DSLR is sometimes categorized by the number of million pixels. The number is referred to the number of photosite contained by the image sensor. • The Canon 20D DSLR camera is categorized as an 8.2 million pixel digital camera because its image sensor contains exactly of 8.2 million photosites. This specific camera is able to capture digital photographs with a maximum of 8.2 million pixels. In general, a digital camera with more pixels is able to capture more details while provides sharper images. The Image Sensor – The Pixel/Photosite Relations Curtin, P. Dennis (2006). Image Sensor—Capturing the Photograph. <http://www.shortcourses.com/how/sensors/sensors.htm>

  11. Work Cited • Curtin, P. Dennis (2006). Image Sensor—Capturing the Photograph. Retrieved March 7th, 2006, from <http://www.shortcourses.com/how/sensors/sensors.htm> • Halley, Hd (2005). What is the Crop Factor :The Expense of Digital Image Sensors. Retrieved March 5th, 2006, from <http://halley.cc/photo/cropfactor.html> • Wilson, Tracy, & Nice, K., & Gurevich G. (n.d.). Howstuffwork: How Digital Camera Work. Retrieved March 5th, 2006, from <http://electronics.howstuffworks.com/digital-camera2.htm> • Wikipedia.org: Bayer Filter, (2006) Retrieved March 6, 2006, from <http://en.wikipedia.org/wiki/Bayer_filter>