The Canon Camera Guide to Flash Terminology.
Author: TimHarris Total views: 3 Word Count: 544
This general guide will help to explain to you some of the concepts and terms used in relation to Canon EOS flash photography.
Flash and Strobe
The words flash and strobe has been used interchangeably actually to denote the same thing. It all depends on whether you are saying it the British or American way. The American refers strobe as a flash unit whereas the British uses the term to refer to anything which produces blinking lights. Speedlight and Speedlite are also two commonly used terms which create some confusion among those new in the photographic world. Speedlite is actually the brand name for Canon series of flash units while Speedlight is the brand name of Nikon series of flashes.
Guide Number
The guide number is the maximum range of a flash unit when it gives out its flash pulse at its maximum setting. However, if you are using automatic flash metering, the number is not relevant. This number only becomes important when you are involved in manual flash settings.
EV (Exposure Value)
Used for determining the sensitivity of the Auto Focus or (AF) system or exposure metering for film types or a lens, the EV or Exposure Value is a combination of both Aperture settings and Shutter speed. The numbers 1/125 and F2 give an EV value of 9 which can also be obtained from F4 and 1/30.
Dedicated or Non dedicated flash units
Most Camera manufacturers also manufacture their own line of flash units to complement their camera models. These "own" brand of flash units are known as dedicated flash units. The Canon line of flash units is known as the Speedlite series. They are able to work together with the camera proprietary system to give more precision photography. Non dedicated Flash units are those flash units which are manufactured by third party manufacturers. Usually generic in nature, they cannot communicate with the camera proprietary system.
Shoe Mount
The shoe mount is a slide in socket rectangular in shape located on the top mirror/prism housing. This socket is used for affixing the external flash unit to the camera. They are also called "Hot Shoe Mount" as they have an electrical trigger which activates the flash unit. The Canon EOS cameras have additional four electrical contacts within the shoe mount which carries signal data apart from the main flash trigger.
The Redeye Effect
When the light from a flash unit is reflected back into the camera off the walls of the retina, this will produce the Redeye effect which we always see in pictures taken in low ambient light conditions. This due to the fact that the low ambient light condition causes the pupils of the eyes to dilate bigger and the color red is because the retina walls are lined with red blood vessels.
Redeye Reduction
To circumvent around the problem of redeye effect, there are several ways to go about this. One effective way is to move the flash away from the lens or reflect the flash light off the walls onto the subject instead of directly illuminating the subject. Another way is to get the subject to view a bright light just before taking the picture of the subject. This causes the pupils of the eyes to dilate smaller and therefore decreasing the reflective effect of the retina.
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About the Author
Tim Harris is a canon camera enthusiast. For tips on choosing and buying cameras, do check out Canon OS Camera website. Camera 40D Digital Rebel XTI 3D Blog
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