Let us know how you get on Andrew, ask plenty of questions
I'm sure I will
My main thing is trying to figure out the aperture, f-stop, ISO, ect and how they all work together...
It's all about balance as they all affect how light enters and is interpreted by the camera.
Aperture and f-stop are the same thing, as f-stop is the way that the camera measures how wide or narrow the aperture is. The aperture is a diaphragm which sits behind the lens which controls how much light enters the camera. From a creative perspective the wider the aperture (f2.8 on my posh lens) then the more light enters the camera and the more shallow the depth of field, giving you a nice sharp subject with a lovely blurred background. If you want to increase the depth of field and have a whole landscape in focus then you need to close the aperture down (f32), this reduces the amount of light which enters the camera however, which means that the shutter needs to stay open longer, and will require a tripod
Shutter speed is the length of time the camera allows light to pass through the aperture. The shutter speed must always be proportionate to the available light and aperture in order to get the correct exposure and make sure that the image is neither too light or too dark. Fast or slow shutter speeds can be used creatively to either blur or freeze motion depending on what effect you want to achieve.
ISO on a DSLR affects the sensitivity of the sensor, with low ISO's capturing less light with better quality, and high ISO's capturing more light but with more associated noise in the image. So if set to ISO100 you will get a better quality shot, but will require wider apertures or longer shutter speeds to obtain the required light. ISO1600 will allow you to use smaller apertures, or faster shutter speeds, but will leave you with a more noisy shot. Sometimes this is a necessary compromise as it is better to get the shot and it be grainy, than lose it through camera shake or underexposure.
In order to balance these the camera will help a great deal.
By using
Av (aperture priority) you can tell the camera that you want to keep all shots at the widest aperture, either because this will give you an artistic depth of field or because you know that you want to get the fastest shutter speeds available to you in order to freeze action. Or by forcing the camera up to f32 then you are dictating the larger depth of field (area in focus) that you want to achieve in a landscape shot, and leaving the camera to sort out the shutter speed.
If you want to deliberately blur motion in a shot, then selecting
Tv (Shutter priority) and forcing the shutter speed down to 1/160th then you can get good rotor blur on most choppers. The camera will then automatically adjust the aperture to only allow enough light through to correctly expose the shot. Using Tv to select high shutter speeds is less advisable, as there may not be enough light available for the speed that you think you need.
ISO then allows you to push the boundaries a little, for best quality you will want to keep the camera on ISO100, but if you really want to freeze action and get sharp shots of fast motorbikes or birds in flight, then you may up the ISO to 400. If the light is really bad but you can't risk blurred shots from motion or camera shake, then you may push it to 800. If the light is awful, but flash is a no-no, then ISO1600 is better used than missing the shot entirely.
Tv and Av modes are all about choices, and making them yourself rather than letting the camera decide how your shots look creatively. once you have got used to these choices then you can start making all the choices yourself in the M manual mode. This is particularly useful when using flash or when other light sources in a location could fool the light meter in your camera. By using manual you determine exactly what aperture and speed you require, check your results, and then shoot away happy in the knowledge that providing the light available stays the same then your results will be consistent.
My advice.....stick with
Av 99.9% of the time, and simply close or open the aperture to achieve the depth of field or shutter speed you require. You want silky flowing water, close the aperture to bump up the shutter speed. You want to freeze action, open the aperture wide to f2.8 or the lowest f-stop you have to drag the shutter speed right down. Only use
Tv when something with rotors comes past, nothing worse than badfrozenprops
by Omag 2.0 » Mon Jan 05, 2009 5:38 pm 
I have the same problems as you do. I just work from Auto and move up to Tv and Av. I don't use Manual because I take macro and different picture styles I just don't have time to adjust the settings every time light changes.
