Digital Capture Getting it Right

Image Sensor  A silicon chip positioned inside the camera behind the lens;  It captures light bouncing off a subject and converts the light into digital information.  There are many different designs, but the most important factors to consider are—  the image sensor’s pixel count and  physical size.

Pixel Count  The widely cited benchmark of a digital camera is its image sensor’s pixel count, described in mega pixels (MP).  One megapixel is equal to ___________???

Image Processor  Once picture is taken, the information is captured by the image sensor must be handled by the image processor.  Image processor is a dedicated chip inside the camera linked to the sensor.  Functions of image sensor:  Convert info from the sensor into an image file  Controls what pictures look like  Influence some of the camera’s operations. The speed of the image processor affects the rate at which you can take pictures in succession (burst rate) and the time it takes for the camera to pass the image to a memory card.

Image noise and other Digital artifacts  A digital artifact Is a defect or other unwanted element in a picture that occurs during digital capture or in postproduction.  Image noise is the most common type and appears as random, grainlike, and textured color specks.  Some camera models do a better job of minimizing image noise than others. Cameras with large image sensors are less “noisy” than cameras with small sensors.  Noise is most likely to occur when shooting in low light with a high ISP setting. So you can minimize noise by shooting in light that’s bright enough to allow for a low ISO.

Other types of digital artificats  Pixelation: when individual pixels are overly sharp and visible, jagged edges (or jaggies), when lines or edges of objects appear serrated.  Posterization: when gradations of tones or colors appear banded and noncontinuous.  These digital artifacts are more likely to occur in post production than when taking a picture.

File Format  File format refers to how data in a digital file is compressed and saved. This tells the computer how to work with that data.  There are several file formats available when working with pictures digitally. However, only two are usually used for digital capture: JPEG AND RAW

JPEG  Joint Photographic Experts Group  Most widely used image-file format.  With JPEGs, the camera’s image processor makes color, contrast, and other basic decisions about the captured picture, and then compresses it to make it smaller, eliminating any unnecessary data based on those decisions.  Advantages:  Good, useable image file  Reduced file size makes for quicker transmission and editing  More efficient storage  Great for simple uses, such as ing and posting online.  Disadvantages:  Information lost during compression can’t be recovered. This means you have less information to work with, therefore less flexibility in postproduction.  Lost quality means limits in postproduction (making prints,

RAW  An information-rich file format which uses lossless compression. This means that the “raw” picture data captured by the sensor is kept intact—not lost— even if it’s somewhat compressed. Unlike JPEG, where the image processor locks in color, contrast, and other characteristic adjustments, with RAW, you make these choices yourself in post production.  Because they contain so much information, RAW images are much larger than JPEG and relatively slow to process, download and adjust on the computer.  RAW images take up A LOT more storage space than JPEG.  RAW files are identified with by the file extension associated wit the camera you used to take the picture. So, if you shoot RAW with a Canon camera, the extension would be.cr2. If you shoot with a Nicon camera, the extension will be.nef

Other file formats to mention  These are sometimes available in digital capture, but mostly they are used in postproduction.  DNG (digital negative) is a standardized RAW file format, which is uncompressed, information rich, and flexible. They are meant to be stable and widely compatible and use the file extension.dng  TIFF (Tagged Image File Format) is another information –rich file format, commonly a shooting option only in medium-and large-format cameras and a few professional DSLRs. Tiffs are widely used in postproduction. They use.tif as an extension.

Image size  You can set the maximum size of your final image file in the camera menu, as you choose the file format. Most cameras offer a choice of small, medium, or large JPEGs. And many give you the option to choose the level of compression for each size—always choose the largest file size (lowest amount of compression) that you can.  Small JPEGS allow you to capture amny more pictures on your memory card. They also get recorded and processed faster than large JPEGs—and they are quicker to transfer and work on later in postproduction—or just to send in an . But be careful. In the future, you may regret that you have only a small file to work with—if you decide to make a large-format print of a picture.  Almost always, you should set your camera to the largest image size offered. You can always reduce the image size later in postproduction, and not lose quality.

White Balance  Lisght has a strong effect on the color of your picture. Some light is neutral, without a noticeable color bias, whereas other light has a warm (yellow/orange) or cool (blue) cast.  Most fluorescent lights produce a green cast, while tungsten lights are yellow-orange.  Your camera menu has a white-balance setting that allows you to match your image sensor to the color of your subject lighting in order to produce a picture with neutral color—or even “unmatch” it to produce color that is deliberately off.  The default menu setting is auto white balance (AWB), which is the easiest way to achieve balanced color. Set at AWB the camera will evaluate the light and make a white- balance setting for you.  White balance icons:

White Balance Icons These are typical white-balance icons found on a camera menu. With household bulbs lighting a scene, select “tungsten”. On an overcast day, select “cloudy”.

Miscellaneous camera settings  AF: autofocus  AF Lock: Lock in autofocus  Aspect ratio: select image proportions  Autoreview: play back the just-captured picture automatically every time a picture is taken.  Black and white: allows you to make your pictures in black nd white, rather than color.  Exposure mode: Choose from a wide variety of automatic semiautomatic and manual exposure options.  Frames per second (fps) Choose from taking one picture at a time to several per second.  F-stop: selct the size of the lens aperture (opening) when in aperture –priority or manual-exposure mode.

Misc Settings (Cont’d)  Image size: how large or small you want your image file to be.  Image stabilization: activate stabilizing mode to reduce camera/lens shake.  ISO: Control the image sensor’s sensitivity to light.  Live view: Activate a preview of what the camera sees before you take the picture.  Macro: set the lens for focusing close.  Review: Play back captured images manually:  Saturation: adjust the overall color richness.  Self-timer: Activate a time delay of several seconds between puching the shutter button and taking the picture.  Sensor cleaning: Begin automated cleaning procedure.  Shutter speed: set the exposure time.

End of information for this session  Please check back at a later time for more valuable information concerning digital photography.