Panasonic GX850 Flash

Coverage and Range
A small, weak flash with narrow coverage.

Coverage. Flash coverage is rather uneven at wide angle, leaving the corners of our flash target image quite dark at 12mm, thought that's not unusual, especially for a wider-than-average kit lens. Some of the corner shading can also be attributable to the lens itself. We no longer test flash coverage at telephoto, as it is invariably better.

Exposure. Indoors under incandescent background lighting, the Panasonic GX850's flash underexposed our indoor portrait scene at our standard aperture of f/4 at ISO 200, so we let the camera select the ISO. It selected an ISO of 1250 which resulted in overexposed image with very warm colors due to the ambient lighting and high ISO. The shutter speed it selected was 1/50s, which is fair and should help avoid motion blur in most portrait shots.

Manufacturer-Specified Flash Range Test. The Panasonic GX850's built-in flash has a Guide Number of 4.0m at ISO 100. That works out to a range of only about 4.6 feet at f/4 and ISO 200. As you can see above, the Panasonic GX850 produced a good exposure at the rated distance, which means Panasonic's flash rating is credible.