External Flash

Occasionally I get queries from my friends who have recently bought a DSLR that whether they need an external flash for “better” photography specially for indoors. So I thought I would put my few comments of where external flashes can really make the difference and make your photos stand out from the “pop-up” flash photographs.

The “higher” end cameras even do NOT have built-in flashes due to huge limitations of the in-built flash that can become bottleneck to their otherwise excellent image production quality. An external flash provide superior and “more” control over the lighting and exposure of the subject in low light (and even in bright light where you need to fill-flash) situations. Here’s why…

1. Power

This is more obvious than the rest of the reasons but still this tops the list. With the power of the built-in flash (Guide number 13/43 at ISO 100) it becomes really difficult to illuminate “wide” angle shots and thus the edges of the photo remains too dark. With external flash you can get much higher range of illumination (Guide number 43/141 at ISO 100). Additionally an external flash has its own set of batteries thus enabling it to recycle faster so that the flash doesn’t drain the cameras batteries.

Note: It is important to understand that the effective distance of any flash depends on the Aperture and ISO. For example, at f/8 and ISO 100, the built-in flash will be effective only if the subject is within ~5 feet from the camera. Indirectly the range can be increased by decreasing F-stop and/or using a higher ISO setting. But both the methods come at a cost -

(i) less depth-of-field and

(ii) increased digital noise.

While a good external flash unit has about 15 times the power of a built-in unit, with approximately four times the effective distance (there’s some math involved here). Power also becomes critical for bounced flash and fill flash in sunny outdoor conditions.

Example photos for Reference -

i. In-built Flash

(Notice the harsh light changing the natural color shades and the shadow casts)

ii. Bounce Flash

(Notice the even lighting with no shadows and you can even tell that there’s a light inside the lighthouse)

2. Bounced Flash

Probably the next most important thing that dramatically affects the “quality” of the photographs is the ability of “bouncing” the light from the flash onto the subject via ceilings, walls or other objects. The built-in flash will produce a harsh-looking “snapshot” like photo as you cannot control the direction of the built-in flash. While a bounced light of adjustable external flash head can produce a pleasing photograph that doesn’t even look “flashed”. The method produces softer shadows, a brighter background, and more natural-looking results. Of course to be able to effectively bounce of the light, you would need quite powerful flash as with “bounced” light you are lighting up the whole room.

3. Redeye Removal

While we can always remove a red-eye caused by light reflecting off the retina in the back of the eye with dilated pupils (when in

darker indoor areas) using post-processing tools like Photoshop on the photo, it is always advisable to take precautions while taking the photo itself. An external flash does a great job on this. The closer the flash is to the lens, the greater chance of the light coming out of the flash to reflect directly from the retina into the lens. It also depends on the distance between the lens and the eyes. There’s some geometry involved here but the bottom-line is greater the distance between the flash and the lens, the further away the camera can be placed from the human subjects without causing red eyes. As you really cannot control the position of the in-built flash with respect to the lens, an external flash is an excellent solution.

4. Flash Accessories (modifiers, brackets and helper uses)

These are “goodies” that you can attach to your external flash for achieving better effects like “diffusers” that softens the harsh light of the flash. Also index cards can be attached to produce certain cat-eye effects. Another type of modifier is Better Beamer that produces narrow very powerful beams for wildlife shooting at long distances. Again you can get Flash brackets that moves the flash unit further from the lens thus lowering the risk of Red-Eye effect even less. They also help in portrait shots (vertical shots) in reducing shadows from the sides. You can deploy wireless flash setups in order to produce interesting studio like lighting sources from optimum directions. Some flashes include focus assist light that helps the camera’s autofocus system to work efficiently in low light situations. Also you can go for FP Flash (high speed sync) so that you can flash and still useof high shutter speeds. FP flash becomes necessary if you’re using fill flash outdoors but want to use a wide aperture to blur the background and hence need faster shutter speed than the sync speed. These small enhancements can really make a difference when it comes to professional shooting.

As you can understand, the whole area of flash photography is so vast that there are various books written on it and discussions are always ongoing in all photography forums. Adding a flash just adds one more variable to consider along with ten others that can control the quality of the photograph. In my subsequent articles, I will explain the few terminologies (like Guide number, FP Flash, flash exposure, sync speed) in details with example shots along with basic concepts of flash photography. Before that I would recommend getting a flash and also go through an introductory book on flash photography found here.

Which Flash to Buy?

This depends on the compatibility factors and also the power requirements. If you have Canon EOS series DSLR, it is best to go for 580EX if you can afford it. If not, the next best choice would be 430EX (I have this model). If you have a Nikon DSLR, the best bet would be to get SB600 (reasonably priced). There are other alternatives like Sigma and Metz flash units available for both Canon and Nikon DSLRs. Here’s myrecommendations for selecting external flash units with pros and cons.