Nikon D3100 Flash

 

Flash photography has been a particular strength of Nikon SLRs for some time now, and the D3100 follows suit, with its implementation of Nikon's 3D Color Matrix II metering for flash exposures. This advanced exposure metering system takes advantage of subject-distance information relayed by the lens to compute more accurate flash exposures than more conventional systems based on reflected light alone.

Like the D3000 and D5000, flash capability is an area where the Nikon D3100 lacks some substantial capability relative to the company's higher models, though, in that its built-in flash can't serve as a Commander in Nikon's Wireless Lighting System. You can still use the Nikon D3100 to control multiple remote flash units via either an SB-800 or SB-900 flash strobe or Nikon's SU-800 remote commander, but the built-in flash doesn't have that ability on its own.

The flash modes available vary depending on the setting of the mode dial, with some of the more automated/programmed modes restricting your choices. The full list of flash modes includes Off, Auto, Auto+Red-Eye Reduction, Auto+Slow Sync+Red-Eye Reduction, Auto+Slow Sync, Fill Flash, Red-Eye Reduction, Slow Sync+Red-Eye Reduction, Slow Sync, Rear Curtain, and Rear Curtain+Slow Sync. Auto modes automatically pop the flash up as needed in poor lighting or backlit scenes, though the "Flash Off" auto mode prevents the use of flash even in poor light. Fill flash fires the flash strobe with shutter speeds as fast as 1/200 second, helping soften shadows in brightly lit environments. Red-Eye Reduction mode fires the (very bright white) AF-assist light before the main flash exposure, to reduce the effects of red-eye in shots of people. Slow Sync fires the flash at the start of exposure, and uses a slower shutter speed to capture background lighting, reducing the harsh effect of flash shots by allowing more of the ambient illumination into the picture. Finally, Rear-Curtain fires the flash at the end of the exposure, producing light trails that appear to follow (rather than precede) moving subjects. A Manual flash exposure mode is also available, accessed from the bottom of the Shooting menu.

Flash exposure compensation can be set over a range of -3 to +1 EV by holding the Flash and Exposure Compensation buttons down simultaneously, while rotating the Command Dial. (Flash exposure can also be adjusted from the Information Display, using the Multi-Controller arrow keys, which some users may find more straightforward.)

The Nikon D3100 has a 1/200 second maximum X-Sync speed, and its built-in flash is not FP-capable. Basically, this means that the on-board flash can't sync at shutter speeds greater than 1/200 second. There also doesn't appear to be any support for external flash units that are FP-capable, so it seems that 1/200 second is the fastest shutter speed you'll be able to use with the flash, regardless of mode or flash source.

Besides the main flash modes listed above, the Nikon D3100's onboard speedlight can also be used in manual mode, in which you can set its power output to fixed levels of full, 1/2, 1/4, 1/8, 1/16, and 1/32 power. The Nikon D3100's internal flash is fairly powerful, with a guide number of 12 meters or 39 feet at ISO 100 in auto mode, extending slightly to 13 meters (43 feet) in manual mode. The greater range in manual mode is because it doesn't have to expend energy on the metering pre-flash. (Novices should note that 39 feet is the guide number, not the range. Divide the guide number by your lens' aperture setting to produce the actual range in feet.)

Also included on the Nikon D3100 is an external flash hot shoe, just behind the pop-up flash compartment, but there's no separate PC-style sync terminal as found on Nikon's higher-end cameras. (An optional sync terminal adapter for the hot shoe is however available.) The hot shoe accommodates Nikon accessory flash units, as well as a wide range of third party flashes. The full range of flash sync modes remains available for compatible flash units, but third-party models may not support all modes. Different Nikon speedlights offer different features when used on the D3100 as well. Recent Nikon flashes such as the SB-900, SB-800, SB-600, and SB-400 will support i-TTL balanced fill flash and standard i-TTL flash. The SB-900 and SB-800 will also support distance priority manual flash, and auto-aperture flash when used with a CPU lens. Flashes only capable of non-TTL (non through-the-lens metering) auto or manual flash modes include older models such as the SB-80DX, SB-28DX, SB-28, SB-27, and SB-22S.

3D Color Matrix II Flash Metering
As noted above, the "3D" aspect of the Nikon metering system is that it uses subject distance information from the lens (only available with G or D-type lenses) to guide its exposure decisions. This is particularly key with flash exposures, because flash illumination falls off quite strongly as the subject gets further from the camera. The "Color Matrix" part of the name refers to the use of a 420-segment RGB sensor for exposure determination, which significantly improves the accuracy with which the camera can determine various scene types, for lookup in its 30,000-image exposure database. We at IR are huge fans of Nikon's flash technology, it's really a case of technology working perfectly in the service of creativity. The camera just quietly does its job, so you can focus on composition, color, interacting with your subjects, etc. It doesn't remove the creative decisions of how you want to light your subject, it simply removes the technical aspect from the equation. It won't by any means turn a duffer into a pro photographer, but it'll certainly take an average shooter a long way in that direction.

The Nikon D3100 with Nikon's Creative Lighting System
Nikon has long been a leader in flash technology, but in late 2003, they significantly upped the ante with their Creative Lighting System. This system of flashes and supporting camera bodies lets the photographer control up to three separate groups of remote flash units, with an essentially unlimited number of individual strobes in each group. The exposure and operating mode of each group of flashes can be controlled independently, and exposure is metered through the lens (TTL) for all units.

While the D3100 built-in flash can't act as a controller for remote strobes, it's perfectly compatible with the system if you slip an SB-900 flash, SB-800 flash or SU-800 commander into its hot-shoe. The control and creative freedom Nikon's Wireless Lighting system offers is truly amazing: See our Nikon Creative Lighting System review for more info.