1. Shutter speed
2. Aperture size
3. ISO setting
4. Better composition

Exposure is based on three elements. shutter speed, aperture size and the ISO rating of the film being used (or sensor sensitivity). Assuming we are using an ISO rated film or sensor of 200. Lets say our light meter reading is 1/125 @ F11. This will give us the correct exposure. 1/250 @ F 8 will give us exactly the same exposure. Which exposure setting we use depends on other creative considerations. Such as whether we want to freeze the action or show movement. Do we want a shallow depth of field or have everything in focus? Lets say we want to freeze an action shot with no movement visible at all. We would need to select a shutter speed of 1/500 or faster. Using the exposure example given above.( 1/125 @ F11), we would need to open the aperture up to F5.6 if we wanted to use a shutter speed of 1/500. This would balance the exposure. By speeding the shutter speed from 1/125 to 1/500 we are giving the exposure 2 full stops of less exposure. To ensure the same amount of light is passing though onto the film or sensor, we need to open or increase the aperture to allow more light  through. Opening the aperture by 2 stops from F11 is F5.6. see the table below. All these setting give us the same exposure. back to top

 

Shutter speed	aperture
1/4000	F2
1/2000	F2.8
1/1000	F4
1/500	F5.6
1/250	F8
1/125	F11
1/60	F16
1/30	F22
1/15	F32
1/8	F45

 Prosumer and professional cameras provide shutter priority exposure mode, allowing you to vary the shutter speed while keeping exposure constant. back to top

Aperture refers to the size of the opening in the lens that determines the amount of light falling onto the film or sensor. The size of the opening is controlled by an adjustable diaphragm of overlapping blades similar to the pupils of our eyes. Aperture affects exposure and depth of field.

Just like successive shutter speeds, successive apertures halve the amount of incoming light. To achieve this, the diaphragm reduces the aperture diameter by a factor 1.4 (square root of 2) so that the aperture surface is halved each successive step as shown on this diagram.

Because of basic optical principles, the absolute aperture sizes and diameters depend on the focal length. For instance, a 25mm aperture diameter on a 100mm lens has the same effect as a 50mm aperture diameter on a 200mm lens. If you divide the aperture diameter by the focal length, you will arrive at 1/4 in both cases, independent of the focal length. Expressing apertures as fractions of the focal length is more practical for photographers than using absolute aperture sizes. These "relative apertures" are called f-numbers or f-stops. On the lens barrel, the above 1/4 is written as f/4 or F4 or 1:4.

We just learned that the next aperture will have a diameter which is 1.4 times smaller, so the f-stop after f/4 will be f/4 x 1/1.4 or f/5.6. "Stopping down" the lens from f/4 to f/5.6 will halve the amount of incoming light, regardless of the focal length. You now understand the meaning of the f/numbers found on lenses:

Because f-numbers are fractions of the focal length, "higher" f-numbers represent smaller apertures.

Maximum Aperture or Lens Speed

The "maximum aperture" of a lens is also called its "lens speed". Aperture and shutterspeed are interrelated via exposure. A lens with a large maximum aperture (e.g. f/2) is called a "fast" lens because the large aperture allows you to use high (fast) shutterspeeds and still receive sufficient exposure. Such lenses are ideal to shoot moving subjects in low light conditions.

Zoom lenses specify the maximum aperture at both the wide angle and tele ends, e.g. 28-100mm f/3.5-5.6. A specification like 28-100mm f/2.8 implies that the maximum aperture is f/2.8 throughout the zoom range. Such zoom lenses are more expensive and heavy.

Depth-of-Field

Depth-of-Field refers to the zone of in-focus elements, from front to back of the main subject. Depth-of-Field varies inversely with the aperture opening. That is, a wide open (maximum aperture) lens at f/1.4 has very little depth-of-field. If you stop down the lens to f/16, then almost everything from front to back will be sharply in focus.

Just as you decide which shutter speed is depending on how fast the subject is moving, you decide the aperture value depending on how much depth-of-field you want. Of course, you don't always have much choice.

If you're shooting soccer or a hockey match, you have to use faster shutter speeds -- and make do with less depth-of-field. If you're shooting a garden or landscape, however, you will almost certainly want maximum depth-of-field.

Keep in mind that depth-of-field doesn't neatly extend the same distance in front of and behind the point of focus. For any given amount of depth-of-field, roughly one-third of it will fall in front of the point you've focused on and two-thirds will be behind it.
Occasionally, you will come across a situation where all the elements in the scene won't quite "fit" inside the amount of depth-of-field you can manage. By focusing slightly behind the main element, you might just be able to get everything in. There are two other techniques on how to maximize the depth-of-field in your pictures. One is a proven method not many amateurs know of and the other is exclusive only to EOS users. They are known as the HYPERFOCAL DISTANCE and DEPTH-of-FIELD AE respectively. back to top

To measure each film's sensitivity to light, a system of numbers called ISO (International Standards Organization) was devised. Formerly called ASA, these numbers denote film speed, most commonly from very "slow" low ISO films to the "ultrafast" high ISO films. Although the ISO series runs from 6 to 6400, the most common film speeds are ISO 25, 50, 100, 200, 400, 800, 1600, and 3200. There are also films of intermediate ISO, especially ISO 64, 160, and 1000. It's important to remember that as the ISO number doubles, the film is twice as sensitive to light. Thus ISO 200 film would require half as much light as ISO 100 film.

If you use a higher ISO speed film for enlargements, more grain will show up in your photo. If you plan to enlarge or crop your photos, it would be a good idea to use a slower film if you have enough light. Sometimes you have to compromise.

ISO settings are also common in digital cameras, they, as with film affect the sensitivity of the image receptor, in this case the sensor. ISO is the third point of the exposure triangle. As with the shutter speed and aperture moving one full stop halves or doubles the amount of light recorded. An exposure of 1/125 @ F11 on an ISO setting of 200. will be altered by one stop if we changed to an ISO of 400. This is making the sensor more sensitive to light by one stop. To correct the camera setting we must either alter the shutter speed by speeding it up by one stop or close the aperture by one stop. So either 1/250 @ F11 or 1/125 @F16 would give the correct exposure.

Digital SLRs are ideal for newcomers to photography to get out and practice using different settings. With much of the exposure information recorded onto the file, it is easy to get the images onto your PC and see what effects the different settings have had on the final image.  back to top

The traditional laws of composition

1. The law of thirds
2. Positive and negative shapes
3. The golden triangle – equilateral
4. The golden mean – subject near and far

 Space management in the viewfinder

1. Leaving space – see Henri Cartier Bresson for good examples
2. Checking out patterns.
3. Using symmetry – is calming but not very dynamic
4. Using asymmetry – have subject looking into or across frame rather than out of it.
5. Sweeping curve – leading viewer on a diagonal journey form top of frame to its bottom (from one corner to opposite corner (coast line)).
6. shape or form
7. simplicity – less is more
8. reflections and shadows
9. Frame within a frame
10. Using scale
11. Repetition of shapes
12. Eliminating space for a reason – tight cropping
13. Space and movement
14. Focal point
15. Lead – in lines
16. the Dutch angle, using diagonals - to make dynamic and fill frame when photographing strong vertical shapes