Cameras: D100 D7000, lens Nikon 105mm macro, Sigma ring flash Photos taken: facial head shots from approx 6 feet away from subject (f10) and dental intra-oral photos including frontal, right and left laterals taken with a mirror, maxillary and mandibular occlusals taken into a mirror. (all f36)
With the D100, body was set to aperture priority, TTL did not work due to differences in communication protocols, but it still did work in aperture priority. Had to manually boost flash EV to +1.0 for facials, +0.3 for laterals and 0.7 for occlusals. Photos were all generally acceptable.
Sigma ring was replaced with a new sigma ring and D7000 use initiated. TTL is supposed to work but does not seem to work. In aperture priority, everything is dark using the same settings as above. I called multiple dental photography equipment suppliers to see how they sell and recommend their equipment to be used. They all indicate their ring flashes which include the sigma flash, should work in aperture priority and they recommend their clients only use aperture priority.
I contacted Sigma and they said the body has to be set to manual mode because the D7000 will use the flash as a fill flash and not the main flash even though the flash on the body remains closed. In manual mode, settings above do not work, as they are still too dark. I have varied the ISO, the EV, the white balance, and changed the metering to matrix. The photos start to look surreal when the ISO or EV is more than the settings outlined above. To me the metering from the body is not being communicated to the flash, so I assumed the problem was with the new flash.
I sent the flash into Sigma and they said nothing is wrong with it, but do not have the means to test it with way a dentist would use it. Everybody is pointing the finger to someone or something else, but I am no closer to a solution. Does anyone have any thoughts or more importantly a differential way of testing the equipment to establish the source of the problem?