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 maximum distance which a flash unit can reach with its flash pulse is known as the guide number. But if you are using automatic flash metering, this number is not important at all. You will only need to know this number when you are more inclined to do manual settings for your flash.
Exposure value (EV)
EV or Exposure value is the value used for deciding the sensitivity of the AF (Auto Focus) system or exposure metering which respect to film types or lenses. You need to combine the aperture and shutter speed together to get this value. For example, 1/125 and F2 is equal to EV9 which is also equivalent to F4 and 1/30.
Dedicated and Non Dedicated Flash Units
Camera Manufacturers like Canon manufacture their own line of flash units to cater for their own range of cameras. The Canon line of flash units is known as the Speedlite series. These flash units are able to communicate with camera system thus allowing the photographers to enjoy more precision photography. They are called dedicated flash units. Non dedicated flash units are those flash units which are manufactured by third party manufacturers. They are usually generic and are not able to communicate with the camera system.
Shoe Mount
Usually located on the top mirror or prism housing, the shoe mount is a slide-in rectangular socket meant for attaching an external flash unit to the camera. They are also known as "Hot Shoe Mount" as they possess an electrical circuit which will initiate the flash unit once it is attached to the camera. Canon EOS cameras have an additional four electrical points in the shoe mount which transmit data from the flash trigger.
Redeye Effect
A common occurrence with flash photography is the "Red Eye Effect". This happens when the light from the flash unit is reflected back into the camera from it bounces of the red blood vessels of the eyes. The situation tends to occur in environment with low ambient lighting causing the pupils of the eyes to dilate bigger to allow for more light to enter the eyes.
Redeye Reduction
To reduce the problem of Red Eye, one can use several methods. The most effective way is to distance the flash away from the lens or bounce the flash light onto the subject as opposed to flashing directly at the subject. The other way is for the subject to observe a bright light source just before taking the subject picture. This will make the pupils smaller and thus lessening the reflective capability of the retina.
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 maximum distance which a flash unit can reach with its flash pulse is known as the guide number. But if you are using automatic flash metering, this number is not important at all. You will only need to know this number when you are more inclined to do manual settings for your flash.
Exposure value (EV)
EV or Exposure value is the value used for deciding the sensitivity of the AF (Auto Focus) system or exposure metering which respect to film types or lenses. You need to combine the aperture and shutter speed together to get this value. For example, 1/125 and F2 is equal to EV9 which is also equivalent to F4 and 1/30.
Dedicated and Non Dedicated Flash Units
Camera Manufacturers like Canon manufacture their own line of flash units to cater for their own range of cameras. The Canon line of flash units is known as the Speedlite series. These flash units are able to communicate with camera system thus allowing the photographers to enjoy more precision photography. They are called dedicated flash units. Non dedicated flash units are those flash units which are manufactured by third party manufacturers. They are usually generic and are not able to communicate with the camera system.
Shoe Mount
Usually located on the top mirror or prism housing, the shoe mount is a slide-in rectangular socket meant for attaching an external flash unit to the camera. They are also known as "Hot Shoe Mount" as they possess an electrical circuit which will initiate the flash unit once it is attached to the camera. Canon EOS cameras have an additional four electrical points in the shoe mount which transmit data from the flash trigger.
Redeye Effect
A common occurrence with flash photography is the "Red Eye Effect". This happens when the light from the flash unit is reflected back into the camera from it bounces of the red blood vessels of the eyes. The situation tends to occur in environment with low ambient lighting causing the pupils of the eyes to dilate bigger to allow for more light to enter the eyes.
Redeye Reduction
To reduce the problem of Red Eye, one can use several methods. The most effective way is to distance the flash away from the lens or bounce the flash light onto the subject as opposed to flashing directly at the subject. The other way is for the subject to observe a bright light source just before taking the subject picture. This will make the pupils smaller and thus lessening the reflective capability of the retina.
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
