Wondering if you should make that investment in an external flash? This article explains the benefits an external flash has over a built-in flash. (Reported by: Masakatsu Nagayama)
How is an External Flash Different?
An external flash is more powerful for casting light into a far distance, or ensuring sufficient coverage when shooting with an ultra-wide angle length.
The built-in flash (also called a pop-up flash) that comes with most action camera flashlights, including DSLRs and mirrorless cameras, is indeed very convenient to use. However, it also has a number of limitations, which can be overcome by using an external flash.
1. Flash-to-Subject Distance
Flash-to-subject distance refers to the maximum distance that the subject can be from the flash to ensure that it is illuminated. The light from the flash is unable to reach subjects that are located beyond this distance, and the image will turn out underexposed as a result.
Built-in flashes generally have a maximum flash-to-subject distance that is limited to 1 to 3 meters at ISO 100.
External flashes have a higher flash power than built-in ones, with some capable of illuminating subjects that are located more than 10 meters away. In other words, you can use them to ensure sufficient lighting on subjects that are located further away from the camera.
2. Angle of Coverage
The angle of coverage, also known as the flash angle, refers to the area that the light from a flash can cover in terms of the lens angle of view (focal length).
Built-in flashes have an angle of coverage designed to cover an angle-of-view equivalent to the wide end of a standard zoom lens. This means that if you are using any focal length that produces an angle-of-view wider than the angle of coverage of the flash (for example, a wide-angle lens), the edges of your image might still appear dark. If you are using a lens with a long body, you might also get the dreaded “lens shadow”, where the shadow of the lens is captured in the image.
External flashes, on the other hand, can cover a wider flash angle. This means that they can brighten the entire image regardless of the type of lens used—even if you are using a wide-angle lens.
3. Direction of Light
Built-in flashes can light a subject only from one direction—the front. This could be sufficient for some scenes, but in others, such as in portrait photography, the front lighting from head-on could make the subject appear flat.
Meanwhile, many external flashes, including Canon’s Speedlites, feature flash heads that can be rotated or tilted to achieve different lighting directions and angles. Canon’s Speedlites can also be operated off-camera for even more flexibility in lighting direction.
Although a built-in flash does not need to be carried around separately, it also has disadvantages such as insufficient flash power and ability to cast light only in the front direction. To produce more professional results, the use of an external flash is recommended.
An external flash unit that can be attached to the hot shoe is also known as a “clip-on flash”.
What Other Advantages Does an External Flash Have?
It has other features that provide you with more freedom to capture photo opportunities and create effects not possible with a built-in flash.
1. A Shorter Flash Recycle Time
An external flash has its own power source, which enables it to recycle faster. In other words, the recovery time is short from the point the flash is fired until it is ready for the next flash, which means the photographer is less likely to miss out on a photo opportunity.
2. More Creative Possibilities
If your external flash has an adjustable flash head, you can tilt and change the angle to carry out bounce flash, which results in softer lighting that is less harsh. If the external flash supports features such as wireless firing and linking with multiple flash units, you can achieve effects that are even more sophisticated.
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