Wednesday, December 10, 2008

Explanation of the Canon EOS Flash Photography

By Tim Harris

Many Canon EOS camera users often end up confused when they try to use the available modes on the camera without understanding how they function. The reason is that the AV (aperture Priority) mode, TV (Shutter Priority) mode, P (Program) mode and M (Manual) mode handle the metering operation differently. This is especially obvious when you are photographing under condition of low ambient light conditions. Here in this guide, we will give you a breakdown of how the various modes function so that you will know how they work under differing conditions. The FP mode is also assumed not to be turn on in this guide.

The P (Program) Mode

With the P mode, The Shutter speed is set to the highest possible speed to let you be able to hold the camera with your hands. You will also not have the problem of motion blur since the shutter speed is set fast enough to compensate for the low ambient light conditions. The P mode also functions when the ambient light is high. Under High ambient lighting conditions, the Camera will assume that the foreground will be flashed filled. Therefore, the output of the flash will be low powered. Conversely when the ambient light is low, the flash will be adjusted to give a higher output. The shutter speed will also be adjusted accordingly. But the picture will result in having a dark background.

The TV (Shutter Priority) Mode

Under this mode the camera will let you decide the shutter speed. It will instead choose an aperture priority to suit the shutter speed to ensure that the exposure level for the background is correct. The duration of the flash pulse will be determined by flash metering. In short, the camera always operates in fill flash mode under the TV mode as opposed to P mode. The Canon EOS system will also warn you if the background is too dim. This will be shown when the maximum aperture value of the camera lens starts to flash in the viewfinder. When this occurs, you should slow down the shutter speed. You will also require a tripod if you wish to avoid motion blur.

AV (Aperture Priority) Mode

With this mode, you can fix the depth of field (DOF) by adjusting the lens aperture. The camera will determine the correct shutter speed for exposing the background to the correct level. The metering system will decide also how long the flash pulse should be. You have to note that if the shutter speed is low, you will need a tripod stand to prop up the camera instead of using your hands to hold the camera. This is because at low shutter speed, your pictures will end up having motion blur. Just like the TV mode, the camera operates fill flash mode. There are several cameras which have the exception to this mode. The canon EOS10/10s and the Canon Elan II/ EOS 50 models has a unique function will lets you lock the X-Sync speed to the Shutter Speed.

M (Manual ) Mode

When you use the M Mode, you will determine the aperture and shutter speed of the camera. The exposure level will also be decided by you. The camera will just determine the correct flash duration to illuminate the foreground using the flash metering system. - 15437

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