F Stop: This term relates to the aperture of the camera's lens. The lower the number (f2.8) the wider the aperture (hole) in the diaphragm of the lens. Conversely, the higher the f stop number ( f22) the smaller the aperture in the diaphragm of the lens. Some cameras/lenses go down to f1.4, some cameras/lenses go up to f45.

See http://en.wikipedia.org/wiki/F-number for examples of the effects of using different apertures.

Depth Of Field: This relates to how much of a shot is in focus. Low f stop numbers (f2.8) will result in a narrow depth of field (DOF) and a high f stop numbers (f22) will result in a deep depth of field (DOF) See http://en.wikipedia.org/wiki/Depth_of_field
for examples and more information.

Exposure: The amount of time the shutter is open. Obviously, a small aperture will require a longer exposure whilst a wide aperture will need a shorter exposure. See http://en.wikipedia.org/wiki/Exposure_%28photography%29 and http://en.wikipedia.org/wiki/Exposure_value for more details and examples.

In practical terms, useful for the urbexer with a digicam.

Set your f stop to f8 and increase your exposure length to 10/15 seconds. You should be able to see on the LCD screen the correct combination of exposure vs f stop which will produce an acceptable image. If you can't see anything on the LCD and you're sure it's switched on, either lower the f stop until you see the preview image appear on the LCD or shine a torch on the subject you're trying to shoot. Take a shot.

Assuming you've captured an image you can see, adjust either the f stop, the exposure length (or both) until you have an
acceptable image. This process is known as bracketing. http://en.wikipedia.org/wiki/Bracketing

Example of shutter speed bracketing: http://upload.wikimedia.org/wikipedi..._Greenwich.jpg

If you want to capture a shot of a long room, for example, you would want the f stop set to give a good depth of field so you would use f8 or higher with a long exposure. If, however, you wanted to do a close up shot of something you could easily
get away with using f2.8 with a shorter exposure.

Composition: http://en.wikipedia.org/wiki/Composi...visual_arts%29

Crucial to understand if you want to get some decent shots.

You're shooting digital so you don't have the expense or delay you have with film so don't hold back, shoot a hundred or more frames and bracket the shots like your life depends on it . Take 100 shots, expect five photographs. Eventually, you'll get to know how your camera behaves in various lighting conditions and getting a decently exposed image will become almost second nature and the ratio of photographs to snaps will increase.

It is important that you use a tripod but it's just as important that you make use of your cameras self timer function. This will almost certainly eliminate the small amount of camera shake you will get when you press the button to release the shutter. I set my aperture to whichever depth of field the shot requires, I set my exposure length, I ensure that the camera is set to 2 second self timer, and then I press the shutter release and stand back. I let the camera do it's job of capturing the image, then I check the composition, bracket the aperture and exposure and repeat the process until I'm happy with the result.

ISO: It's easier for me to quote the opening paragraph from the wikipedia entry for ISO http://en.wikipedia.org/wiki/ISO_5800:1987

"Film speed is the measure of a photographic film's sensitivity to light. Stock with lower sensitivity (lower ISO speed rating) requires a longer exposure and is thus called a slow film, while stock with higher sensitivity (higher ISO speed rating) can
shoot the same scene with a shorter exposure and is called a fast film"

In B&W Photography the traditional fast/slow films are Ilford FP4 (slow ASA100) and Ilford HP5 (Fast ASA400) There is some interrelationship between fast and slow films and the amount of contrast you get from them with the slower films being
less contrasty and the faster films giving more contrast. From memory, this is to do with the size of the silver halide crystals used in the production of the film stock. http://en.wikipedia.org/wiki/Photographic_film

Translating that into the digital age:

Fast (high) 800 - 3200 ISO = Large Crystals = More Grain = More Noise
Slow (low) 50 - 400 ISO = Fine Crystals = Less Grain = Less Noise

Lower the ISO - Less Contrast - Decreased Noise - Increased Exposure Time.
Raise the ISO - Gain Contrast - Increase Noise - Decrease Exposure Time.

In practical terms for the urbexer with a digicam: It's best to leave the ISO set relatively low, 200 seems to do it with my camera in most situations but your camera may be different. This is why experimentation with the settings of your camera is essential.

White Balance: This could become a nightmare for me to cover, everyone's camera is different and setting the white balance is totally dependent on location, time of day, tungsten or fluorescent lighting. I could be here for days so I'll post the link to the wikipedia explanation. http://en.wikipedia.org/wiki/White_balance

Tweaking Your Camera: If your camera has a 'my colours' setting as found on Canon cameras, try setting the colours to vivid and the White Balance to Cloudy or Indoors. You may love the effect, you may not. Try Sepia Tone, B&W, Try using
the tungsten setting on a sunny day. Experiment !

RTFM: Read The Fskin Manual !

I cannot emphasise enough the importance of RTFM. Go through each section one by one until you get it. If you still don't get it:

STFW: Search The Fsking Web !

Someone else is in the same situation as you with the same camera and they will probably have asked the same questions you are asking. Chances are, they will have been provided with an answer. So googling a question such as "depth of field explained" for example, will get you these search results.