Understanding Resolution Digital Cameras Ann Ware Bald Knob

Understanding Resolution & Digital Cameras Ann Ware Bald Knob High School 1

Resolution Understanding digital cameras requires that we know how resolution works. Resolution is determined by how many pixels (picture elements) or dpi (dots per inch) are available. The image you see is simply a grid of small squares or circles filled in with color. The more squares or circles—the sharper the image. 2

Measuring Resolution is measured by the number of horizontal pixels times the number of vertical pixels ◦ Example: 3072 x 2304 3

Megapixels The quality of a picture is measured by its resolution —how many pixels it has; the current measurement is megapixels A megapixel is a grid containing one million pixels (one million squares of color)—technically, that is an image with a resolution of 1024 x 1024 pixels 4

Resolution With computer graphics, there are three different resolutions to consider: ◦ the image’s resolution (pixels) ◦ the monitor’s resolution (pixels) ◦ the printer’s resolution (dpi) 5

Image Resolution The image’s resolution is measured in pixels. Most cameras allow you to change the resolution before you take the picture. The higher the resolution— the clearer the image— the bigger the file size. 6

Monitor Resolution Monitor resolution is measured in horizontal and vertical pixels ◦ Example: 1024 x 768 If an image is taken at 1280 x 960, but your monitor can only display 1024 x 768— that’s as good as it gets! 7

Printer Resolution Printer resolution is measured in dpi—dots per inch. The quality of the printed image is going to be determined by both the resolution of the image AND the resolution of the printer. 8

Point and Shoot Cameras Most digital cameras designed for the consumer (vs. professional) are point and shoot cameras They fall into three categories: subcompact, compact and super zoom The camera lenses are built-in (not removable) Basic features typically include auto focus, auto exposure and built-in flash Not appropriate for action photography because of lag time 9

SLR Cameras (Single Lens Reflex) With an SLR camera, you see exactly what the lens sees You can change the lens on a digital SLR ◦ You choose the lens based on the type of photography; example: portrait photography vs. sporting events vs. landscape photography, etc. SLRs produce higher-quality photos than point and shoot cameras An SLR has a near-zero lag time, and is ideal for action photography 10

Other points to consider When purchasing a camera, you should also research the following specifications: ◦ Storage Capacity ◦ Transferring Images ◦ Power Source ◦ LCD vs. Optical View Finder ◦ Zoom ◦ Image Stabilization ◦ The Exposure Triangle (Aperture, ISO, Shutter Speed) 11

Storage Devices Memory Card Internal Memory (RAM) The number of pictures you can take before sending them to your computer is determined by two things: The resolution of the image The type of storage 12

Transferring Images Card reader USB cable Bluetooth 13

Power Source Regular Batteries Rechargeable batteries ◦ Alkaline ◦ Nickel-metal hydride (Ni. MH) ◦ Lithium-ion (Li-Ion) AC 14

LCDs vs View. Finder LCD—Pro’s ◦ Shows you the exact image that will be recorded ◦ Easy to view … delete images, etc. ◦ Displays menu n LCD—Con’s ◦ Drains battery—uses ½ life of battery ◦ Difficult to see in bright light n View Finder—Pro’s n n Uses less battery Easier to see images in bright light View Finder—Con’s n n Shows close approximation of the final image—not the real thing Difficult for some people to see 15

Zoom Optical zoom actually enlarges the image—measured in X ◦ example: 8 X—increases an image 8 times Digital zoom takes a portion of an image an enlarges it electronically; the image loses resolution when the camera enlarges it; also measured in X Macro zoom allows you to take close-up pictures of objects that are small and enlarge them so they appear larger. 16

Image Stabilization A feature in digital cameras that reduces the vibrations that can occur when taking a picture. ◦ Vibrations commonly occur when shooting at slow shutter speeds, with longer lenses or with digital zoom. ◦ Also called anti-shake 17

The Exposure Triangle Exposure is the total amount of light you let into your camera. ◦ Too much light results in an over-exposed image where there areas of bright white or ’blow-outs’. These areas contain no detail or color. ◦ Too little light and an under-exposed image leaves parts of your image too dark to make out details. The three components to exposure are ISO, shutter speed and aperture 18

The Exposure Triangle ISO—the measurement of how sensitive the image sensor in the camera is to light. ◦ Measured in numbers 100, 200, 400, 800, etc. ◦ Use a lower number when smooth crisp images are need and you have plenty of light. ◦ Higher numbers are used when light is limited, you do not want to use a flash, or the subject is moving; may result in grainy images 19

The Exposure Triangle Shutter Speed—the amount of time the shutter is open—which determines how much light is captured in the recording process ◦ Measured in seconds: super fast 1/2000 second to 30 seconds ◦ The slower the speed, the longer light can enter the camera. Appropriate for shooting pictures in darker situations; also great for freezing action and movement 20

The Exposure Triangle Aperture—the camera feature that regulates the amount of light that passes through the lens by controlling the size of the opening in the lens ◦ Described as the f/stop (a stop is a change in setting) ◦ The smaller the number the wider the lens will open 21

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