In my school days I started to use traditional manual film camera. But after the invention of digital cameras, I chucked away my manual camera and plunged into point & shoot mode. Over a decade, I never thought of going back to manual camera as I don't have patient to adjust every time. However, when my compact camera finally gave up its soul, I had look for another one. I thought of buying a Digital SLR. But money was a constraint! So, finally settled down for a semi automatic digital camera (also known as Bridge camera).

As I was revising my long forgotten camera knowledge, thought of writing it down here in concise form so that I can refer it in future.

Film speed = measured in numbers like 50, 64, 80, 100, 200, 400, 1600, 3200, 6400. Lower the number, less grain/noise captured in photo (which is good). You should always try to shoot images in lowest ISO speed possible for best quality of image. However, higher ISO films are most sensitive to low light and so you need to use higher film speeds (200 and above) in indoor or low light conditions. Outdoor photos in sunny days should be shot at 100 ISO or lower.

Aperture = the measurement of opening of the lens. Measured in F#. Higher F# means smaller opening and vice versa.
For example, F1.8 will allow more light (= more exposure) to enter on camera compared to that of F16.

Shutter speed = duration of lens opening. Longer duration means more exposure ( = more light) and vice versa. Measured in fraction of second. 1/60 shutter speed means shutter will open for 1/60th of a second.

Aperture and shutter speed relationship as followed in most compact digital cameras. [Not entirely sure about this tabulation - I need to double check]

F1.8 F2.8 F4 F5.6 F8 F11 F16
1/250 1/125 1/60 1/30 1/15 1/8 1/4

Shutter speed range - 4/1 to 1/2000 s

Large aperture = smaller F# = more light = shallow depth of field (subject is nearer) = only subject in focus = portrait

Smaller aperture = larger F# = less light = distant depth of field (subject is far away) = everything in focus = landscape

Aperture priority mode = you set aperture value and camera decides appropriate shutter speed
Shutter speed priority mode = you set shutter speed value and camera decides appropriate aperture
Manual mode = you select both aperture and shutter speed

Lens focal length

Compared to traditional 35 mm cameras, lens of 28 mm focal length or below is considered in wide angle territory. Lens below 20 mm is very good wide angle. From 11 to 18, it is considered ultra wide angle. At extreme, 6 mm lens is known as fish eye. Very wide angle lens do show barrel distortion.

Standard fit lens of most SLR cameras vary from 10 to 60 mm. So, most of them have built in wide angle lens. They use separate lenses for telephoto/zoom.

CCD sensor - This is equivalent of film in digital cameras. Larger the CCD sensor size, more details can be captured. Most digital compact cameras has small CCD sensor (4x6 mm). The DSLR cameras have much bigger CCD sensor size (~ 16x24 mm) for which they can capture rich vividly colored images. CCD means Charged Couple Device. Traditional 35 mm films have size of 24x36 mm. Larger CCD is more expensive. Sensor size difference is the fundamental reason why DSLR picture quality is far better than those taken by digital compact cameras.

A 35 mm camera film camera has sensor size 24x36 mm. Most DLSR cameras has sensor size 15x23 mm.

That means, for same lens, a DSLR will crop an image compared to what it would have been shot with 35 mm camera.

Conversely, the crop event can be visualized as if the DSLR has a different focal length lens compared to 35 mm camera.

So a 18-55 mm lens in DSLR becomes 29-88 mm in terms of equivalent 35 mm lens!

Now say a compact digital camera has sensor size /2.3" which equals 4.62x6.16 mm, so crop factor = 36/6 = 6

However, digital compact cameras state their focal length in 35mm equivalents! So a 27-486 mm lens stated in digital compact camera will have actual lens size 4.5-81 mm.

http://en.wikipedia.org/wiki/Crop_factor 
http://en.wikipedia.org/wiki/Charge-coupled_device

Shooting techniques

Panorama

All images, using which you will stitch panorama, must have uniform exposure. Otherwise they will look awkward (with different brightness in final panorama) or you painstaking photo-editing to adjust exposure in your computer. Any decent panorama sticher software will be able to stitch images to generate stunning looking panorama.

To ensure uniform exposure, you must lock exposures between images (if your camera allows this). Otherwise, if you camera has panorama assist mode, it will do this for you by itself. If you camera has neither, they you can take panoramas only in bright sunlight (without any shades) where your camera is unlikely to vary exposure between shots.

Landscape

For landcape shooting in bright sunlight, use higher F# (over F5 possibly F11 or F16) and lower shutter speed. Subject is considered at infinite length for this shot. Keep flash off. Use lowest film speed possible. When you select Landscape mode in compact cameras, internally they adjust settings like this. If sky is overcast, use a slower shutter speed and/or larger aperture (= lower F#).

Portrait

Subject should be in focus. Here you have shallow depth of field, so use lower F# like F2.7. Adjust film and shutter speed depending on where you shoot in outside or indoor. For night indoor, you might need to use flash.

Moving objects

Since the object is moving (eg. moving car or athlete), you need to use a high value of shutter speed (typically 1/250 or faster depending on speed of object). Many compact cameras have sport mode for this shots. Some cameras offer burst mode - where you can press the shutter button for sometime and camera takes photos continuously.

Environmental factors

The best photos are shot in bright sunlight! In fact, even a very cheap camera takes brilliant shots in sun. The capability of camera shows up during overcast days, indoor shots and super zoom (macro) levels.

Mega Pixel (and myth)

All cameras now advertised with megapixel values. Does a higher megapixel means better image? A mega pixel is calculated as = (# of horizontal pixels) x (# of vertical pixels) / (1024 x 1024).

So, an image size of 2048 x 1536 / (1024x1024) is 3 mega pixels.

640x480 = 0.3 MP = VGA quality
3624 x 2448 = 7.6 MP etc.

All the pixels are constrained by CCD sensor size. For most digital compact cameras, the sensor size is quite small. For same sensor size, an 8-MP camera will have more number of smaller pixels compared to a 3-MP camera - but distributed over same area! If you peek your nose over a television screen, you will see lots of tiny dots. These are pixels. More mega pixel means smaller dots. If the color changes between neighboring dots, smaller the dots are, smoother the changes will appear. That's the story behind higher mega pixels. However, a true TV viewing experience does not always depend on resolution (MP for camera) but also on how big the screen is (say 42 inch screen against 26 inch LCD). The screen size is equivalent to CCD sensor size!

Now see the difference, when people talk about TVs, they measure screen size but when talking of cameras, they don't talk sensor size but number of pixels! Otherwise how would camera manufacturers make you believe more MP means better?

Thus the correct comparison for quality of image between two cameras is this = square root of (higher MP / lower MP).

For a 3-MP and a 6-MP camera, quality difference comes to = sqrt(6/3) = 1.41. So, one is only 41% better than other not the 200% as media make you believe! Buyers beware!

Sample specification of the Fujifilm S8000fd camera, which I now use

ISO film speed - 64/80/100 to 6400 in double increment
Aperture range - F2.8 to F8
Shutter speed range - 4/1 to 1/2000 s
Lens range (35 mm equivalent) - 27 to 486 mm