Panasonic GF3 Flash
The Panasonic GF3's built-in flash has a Guide Number (GN) rating of 6.3 meters (20.7 feet) at ISO 160. That's a actually a little weaker than the GF2's 6m (19.7 ft.) rating at ISO 100, as translated to ISO 100, the GF3's Guide Number would only be about 5m. That's a lot weaker than most digital SLRs, which are typically rated at 12 or 13 meters, but still better than no flash when your subject is close or you need some fill-flash.
The Panasonic GF3's flash is released manually by pushing the Flash Open button on the camera's rear panel. Raising the flash enables it, though it can be defeated using a menu selection. It never pops up automatically like some models, which can be good or bad, depending on your point of view. A novice would probably appreciate an auto-pop-up flash, but someone with experience might think it a nuisance.
When open, the flash doesn't extend very high, so at wide angle longer Micro Four Thirds lenses could cast a shadow when the lens hood is attached, especially now that it's aligned with the lens. Red-eye could also be more common. The Panasonic GF3's flash is disabled by pressing down until it clicks shut.
The Panasonic GF3's built-in flash has seven modes: Auto, Auto with Red-Eye Reduction, Forced On, Forced On with Red-Eye Reduction, Slow Sync, Slow Sync with Red-Eye Reduction, and Forced Off. Flash modes are changed via the Record menu, and available settings vary depending on exposure mode. A Digital Red-Eye Reduction feature is offered, which when enabled, will attempt to remove red-eye after the photo is taken, via post-processing. A second curtain synchronization mode is not offered. X-Sync (the maximum shutter speed with the flash enabled) is 1/160 second, a bit below average these days, and there is no mention of a higher-speed FP (focal plane) mode. There's also no wireless flash support in the Panasonic GF3.
The Panasonic GF3 does not allow you to adjust flash and ambient exposure independently of each other, as there is no separate flash exposure compensation feature. Flash exposure bracketing is not supported, and there is no manual flash mode where output level can be set as a percentage of full power.
Unlike all SLRs and even the GF2, the GF3 does not have a hot shoe or accessory port for mounting an external flash unit, which is unfortunate as the internal flash is quite small and therefore rather weak.
Flash Test Results
Coverage and Range
Modest flash power with uneven coverage using the 14mm kit lens. Higher than average positive exposure compensation required.
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| 14mm @ f/2.5 | |
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| Normal Flash +1.0 EV |
Slow-Sync Flash Default |
Coverage. Flash coverage is very uneven and dark at 14mm, leaving the corners of our flash target image quite dark, though some of the fall-off is from the lens itself. We measured about 0.8 f-stop of fall-off in the corners from the lens, but the above shows much more than that.
Exposure. Indoors under incandescent background lighting, the Panasonic Lumix DMC-GF3's flash performed modestly in our standard test, as a higher than average positive exposure compensation of +1.0 EV still resulted in dim results. (Note that the GF3's flash output cannot be adjusted separately from the ambient exposure.) The camera's slow-sync flash mode required no compensation, though the longer shutter time results in a much warmer cast from the ambient background lighting.
| Flash Range | |||||
|---|---|---|---|---|---|
| 6 ft | 7 ft | 8 ft | 9 ft | 10 ft | 11 ft |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
| 12 ft | 13 ft | 14 ft | 15 ft | 16 ft | |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
 1/60 sec f2.5 ISO 160 |
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ISO 160 Range. We normally shoot this series at ISO 100, but the Panasonic GF3's minimum ISO is 160. Flash exposure started out bright at 6 feet (at least in the center), and remained fairly bright out to about 8 feet, but brightness fell off gradually from there as distance increased.
| Manufacturer-Specified Flash Range |
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 8.3 feet ISO 160 |
Manufacturer-Specified Flash Range Test. Panasonic rates the GF3's flash with a Guide Number (GN) of 6.3 meters at ISO 160. That works out to about 8.3 feet at an aperture of f/2.5, the maximum aperture of the 14mm kit lens. In the shot above, the Panasonic GF3 produced a good exposure (at least in the center) with the 14mm kit lens. The center of the flash target was well exposed, indicating the flash's GN rating is fairly accurate. Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We've now also begun shooting two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of the specific claims.
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