Nikon D3100


Reflex cameras, both the SLR and the TLR types, are equipped with mirrors that reflect in the viewfinder the scene to be photographed. The twin-lens reflex is box-shaped, with a viewfinder consisting of a horizontal ground-glass screen located at the top of the camera. Mounted vertically on the front panel of the camera are two lenses, one for taking photographs and the other for viewing. The lenses are coupled, so that focusing one automatically focuses the other. The image formed by the upper, or viewing, lens is reflected to the viewing screen by a fixed mirror mounted at a 45 degree angle. The photographer focuses the camera and adjusts the composition while looking at the screen. The image formed by the lower lens is focused on the film at the back of the camera. Like rangefinder cameras, TLRs are subject to parallax.

In the SLR type of reflex camera, a single lens is used for both viewing the scene and taking the photograph. A hinged mirror situated between the lens and the film reflects the image formed by the lens through a five-sided prism and onto a ground-glass screen on top of the camera. At the moment the shutter is opened, a spring automatically pushes the mirror out of the path between lens and film. Because of the prism, the image recorded on the film is almost exactly that which the camera lens “sees,“ without any parallax effects.

Most SLRs are precision instruments equipped with focal-plane shutters. Many have automatic exposure-control features and built-in light meters. Most modern SLRs have electronically triggered shutters; apertures, too, may be electronically actuated or they may be adjusted manually. Increasingly, camera manufacturers produce SLRs with automatic focusing, an innovation originally reserved for amateur cameras. Minolta's Maxxum series, Canon's EOS series, and Nikon's advanced professional camera, the F-4, all have autofocus capability and are completely electronic. CPUs (central processing units) control the electronic functions in these cameras (see¬†Microprocessor). Minolta's Maxxum 7000i has software “cards“ which, when inserted in a slot on the side of the camera, expand the camera's capabilities (see¬†Computer).

Autofocus cameras use electronics and a CPU to sample automatically the distance between camera and subject and to determine the optimum exposure level. Most autofocus cameras bounce either an infrared light beam or ultrasonic (sonar) waves off the subject to determine distance and set the focus. Some cameras, including Canon's EOS and Nikon's SLRs, use passive autofocus systems. Instead of emitting waves or beams, these cameras automatically adjust the focus of the lens until sensors detect the area of maximum contrast in a rectangular target at the center of the focusing screen.

Creative Modes | Auto Modes | Self-Timer | Focus Modes | Lenses | Live View | Back Button Focus
Blinkies | Histogram | AE-L | AF-L | Care of Equipment | Diopeter | Image size and Quality | Flash Modes| ISO | Shutter Priority | Aperture Priority | Image Playback | D3100 Cheat Sheets | Filter effects | Auto & Creative Modes | Information Display | Viewfinder | Shoting Movies | Release Modes| Focal length



Keep Your Eye in the Viewfinder

If you keep your eye in the viewfinder, you will usually be able to find all your settings. Some photographers use the back LCD to check their exposure settings rather than using the viewfinder. When this is done, you just might miss the shot. You can read most of these settings in the viewfinder and it will allow you to make changes as necessary. All it requires is a bit of muscle memory in terms of remembering the buttons.

Focus Modes on D3100 Nikon D3100 Manual Cheat Sheets Nikon D3100
18-55mm lens
Flash Single Point Focus and Focus Lock Image size and quality
Built-in Flash Flash Modes D3100 Cheat Sheets - PDF
Camera Filter Effects Image Overlay (combing 2 photos) Memory card capabilities
Specifications Getting to know your camera (parts) Live View
Shooting Movies Release Modes  


Camera Operation

Aperture - Ms. Gregson

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