Understanding Resolution & Understanding Resolution &

DigitalDigital CamerasCamerasAnn Ware

Bald Knob High School

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ResolutionResolutionUnderstanding 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 ofsmall squares or circles filled in with color. The more squares or circles—the sharper the image.

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Measuring ResolutionMeasuring Resolution

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

MegapixelsMegapixelsThe 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 1024x1024 pixels

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ResolutionResolutionWith computer graphics, there are three different

resolutions to consider:◦the image’s resolution (pixels)◦the monitor’s resolution (pixels)◦the printer’s resolution (dpi)

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Image ResolutionImage ResolutionThe 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.

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Monitor ResolutionMonitor ResolutionMonitor resolution is measured in horizontal and vertical

pixels◦Example: 1024x768

If an image is taken at 1280x960,but your monitor can only display 1024x768—that’s as good as it gets!

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Printer ResolutionPrinter ResolutionPrinter 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.

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Point and Shoot CamerasPoint and Shoot CamerasMost digital cameras designed for the consumer (vs. professional) are

point and shoot camerasThey fall into three categories: subcompact, compact and super zoomThe camera lenses are built-in (not removable)Basic features typically include auto focus, auto exposure and built-in

flashNot appropriate for action photography

because of lag time

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SLR Cameras SLR Cameras (Single Lens Reflex)(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 camerasAn SLR has a near-zero lag time, and is

ideal for action photography

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Other points to considerOther points to considerWhen 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)

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Storage DevicesStorage DevicesMemory CardInternal Memory (RAM)

The number of picturesyou can take before sendingthem to your computer is determinedby two things: The resolution of the image The type of storage

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Transferring ImagesTransferring ImagesCard reader USB cableBluetooth

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Power SourcePower SourceRegular BatteriesRechargeable batteries◦Alkaline◦Nickel-metal hydride (NiMH)◦Lithium-ion (Li-Ion)

AC

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LCDs vs ViewFinderLCDs vs ViewFinderLCD—Pro’s

◦Shows you the exact image that will be recorded

◦Easy to view … delete images, etc.

◦Displays menuLCD—Con’s

◦Drains battery—uses ½ life of battery

◦Difficult to see in bright light

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View Finder—Pro’s Uses less battery Easier to see images in

bright light

View Finder—Con’s Shows close

approximation of the final image—not the real thing

Difficult for some people to see

ZoomZoomOptical zoom actually enlarges the image—measured in X

◦example: 8X—increases an image 8 timesDigital 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.

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Image StabilizationImage StabilizationA 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

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The The Exposure TriangleExposure TriangleExposure is the total amount of

light you let into your camera. ◦Too much light results in an over-exposed image where there are

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

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The The Exposure TriangleExposure TriangleISO—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

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The The Exposure TriangleExposure TriangleShutter 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

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The The Exposure TriangleExposure TriangleAperture—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

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