Image sensor | Shutter | Lens | Aperture | Zoom | Features | Memory Cards

How they Work
Cameras have been around for over 100 years and the technology has changed dramatically, but the concept is still the same.  Whether using a film or digital camera light enters the front of the lens, through the aperture, and is stored on a piece of film or an image sensor.

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Image Sensor
Digital sensors, like film, can have different levels of sensitivity to light called ISO.  As the ISO increases, so does the sensitivity to light.  This higher sensitivity helps with low light situations or action shots allowing for a faster shutter speed  (The shutter is the cover that blocks the sensor until the picture is ready to be taken).  The downfall of higher sensitivity is graininess.  The higher the ISO, the grainier the picture.

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Shutter
In SLR’s the shutter has a mirror on the opposite side of the sensor, which reflects the light into the viewfinder in order to frame the shot.

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Lens
The lens is what controls the zoom, the focus, and a lot of the quality.  A higher quality lens allows light through perfectly without any distortions.

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Aperture
The aperture is the opening that allows light into the camera. Aperture controls the “depth-of-field”, or the amount of the picture in focus.  If the aperture is open wider (ex. an f2.8 or 1/2.8th of an inch) than less of the image will be in focus but, the shutter will remain open for less time to capture fast action.  On the other hand, if the aperture is smaller (ex. f11 or 1/11th of an inch) than more of the image will be in focus, but less light passes through the lens forcing a slower shutter speed.

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Zoom
Zoom is measured in millimeters where 55mm is comparable to what an eye sees, anything less is considered wide and anything more is considered to be a telephoto lens.  Some lenses move and when they do the widest aperture changes (ex. A 18-200mm lens with an aperture that is f4 when wide and f5.6 when zoomed in).  Most cameras image sensors are less than 35mm, which means that there is a multiplication effect.  For most compact cameras there is a multiplication of around 7, thus a 3.7 – 11mm zoom is actually comparable to a 26 – 77mm zoom.  On SLR’s this multiplication ranges from 1.7:1 to 1:1.

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Features
Compact Camera’s
Compact camera features are mostly all meant to make picture taking easier.  Smaller cameras will usually have 3-5X zoom and usually use a lithium ion (proprietary) rechargeable battery. Subcompact cameras will have 10-18X zoom and use lithium ion and “AA” Battery’s.  Many cameras now have face recognition features to keep people in focus and not the background.  One useful feature for low light shooting, or shooting while using zoom, is optical stabilization.  Optical stabilization is an element, or piece, in the lens that counteracts movement to minimize blur.  Digital stabilization is available on almost all cameras but is far less effective in keeping pictures sharp and blur free.  All camera’s will have different Scene Modes, which are preset settings for various shooting situations.  While shooting in the “P” mode (program auto) the camera will give full control over changing flash settings, white balance, self timer, and other settings.

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SLR’s
SLR’s will give a wide variety of settings to make it possible to take a great picture no matter what the conditions are.  Although SLR’s will also have an “Auto” mode and “Scene” modes, the most useful settings are the manual controls.
“P” – Program Auto gives complete control over settings and exposure while it adjusts shutter speed and aperture.
“Av” – Aperture Priority allows for control over the aperture and settings while the camera controls shutter speed. (ideal for portrait photography)
“Tv” – Shutter Priority allows for control over the shutter and settings while the camera controls aperture. (ideal for actions photography)
“M” – Manual mode gives complete control over all settings and makes no adjustment to the shutter speed or aperture.
White Balance – Controls what the camera registers as white based on different “light temperatures” such as cloudy, fluorescent, etc.
Exposure Compensation – allows the user to adjust the exposure (brighten or darken the image)
ISO – changes the sensor sensitivity to light allowing the camera to shoot faster at higher ISO settings when in low light.
Self Timer – delays the shutter (can be useful when using a tripod to eliminate slight camera movement).

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Memory Cards (chart)
On digital camera’s, once the picture is taken it is stored to a memory card.  Different memory cards write at different speeds.  For cameras with more mega pixels, or an ability to shoot at 3fps (frames per second) or more, it is ideal to shoot with a high-speed card capable of recording at 10mbps (mega bites per second) or faster. There are currently four different styles of memory cards: Compact Flash – the largest, usually used in SLR’s
xD -  the smallest memory card used in many Fuji and Olympus camera’s
MemoryStickProDuo – Sony’s style of memory card
Secure Digital (SD) the most common type of memory card used by nearly all camera’s with exception to some SLR’s, Sony camera’s and Olympus cameras.

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