With all the features on your camera, there are really only three. When you use things like Scene modes, they are just preset variations of three camera settings that help ensure you get a good result. In Auto-Mode, you camera makes an evaluation and adjusts these same three settings. You might have a myriad of dials and menu options, which you can pick and choose, but these are often only simplifying the same three settings again!
What are these three camera settings that are the basis of all photography. They are the (the time which your camera's is open and your sensor, or film, is exposed to the reaching it through the . The , this is the diaphragm within the that can be closed or opened to differing sizes to control how much hits the sensor, and the final one is . is the sensitivity of your sensor or film to .
So using these three settings alone, you can basically achieve everything your camera does in auto, semi auto modes, and below is what each one does
The controls how long the coming through the apertures is allowed to hit your film/sensor. Slow speeds can be minutes, seconds, or some of the lower fractions of seconds, like 1/2 a second, 1/4 of a second. Fast speeds are usually very fast, like 1/1000th of a second. The faster the , the more movement is frozen and the of moving objects will be increased. A guideline is that you can generally hand-hold your camera for a that is the inverse of the focal length. So if you are shooting with a 200mm , then 1/200th of a second should allow you to hand hold your camera and get a photo. Shooting at slower speeds either requires a very steady hand or some sort of stabilising (a ). Slower speeds allow blur (like moving water effect).
lets you control the diaphragm in the , thus how much hits the sensor/film for a given . Apertures are fractions. So f2.8 is larger (more open) than f22. These are really 1/2.8th and 1/22nd. So 1/22nd is smaller than 1/2.8, thus an of f22 is smaller than f2.8. An of f2.8 is bigger, so will let more hit the sensor/film for any given than will f22. This is apparent for all selections : f4 is smaller than f2.8, but bigger than f8. The more open you , the less the : distance, front to back, in your photo that will be in focus, outside what you focus on.
So a photo taken at f2.8 will have a shallower area of your photo that is in focus compared to a photo taken at f22.
is the camera's sensor (or film) sensitivity to . Low 's like 100 and 200 are less sensitive to than 800 or 1600. Lower means less noise or grain in your photo than higher 's. As you go higher and higher with an , the more noise/grain is visible in your photos. As you increase the to a larger number and make your sensor more sensitive to , it means you can use a faster .
USING ALL THREE
To get a great photo, you need to decide what your photo is going to look like, before you take it, and then adjust the above three settings to get the result you want. All three settings above are not independent, but they can be independently adjusted. Changing one without changing the others may not get you the photo you want.
Say you want to get a slow milky water effect, you need a slow , but just adjusting the and nothing else might result in your photo being over-exposed. So you set your camera to 1/2second cause you want to show the blur of the water, but then you will likely need a smaller (larger number) otherwise the amount of hitting your sensor could be to much and you end up with pure white areas with no detail in your photo. So with 1/2 second set, you can close down your to say f22 to reduce the through the in the .
It is getting late into the afternoon and you are shooting kids sport. You are using a fast to freeze the action, say 1/500th of a second, but as it gets darker, your photos are coming out dark. You can increase your from 100 to 800 to increase the sensitivity of your sensor to , thus getting shots that are not so dark.
See how all three settings work together to achieve the result you want/need. Learning how / / inter-relate is the basis for all photography. So come to grips with how they work and interact with each other, and you are on the way to understanding your camera more fully and being able to make educated choices in relation to camera settings, to get the photo YOU WANT!