TTL Pre-flash versus Manual Flash
I have had this kind of issue with SONY, but it involved pre-flash concerns, using multiple types of flash sources. Normally, if you go to the "Flash Control" MENU, in the camera, you will see three selections to choose from:
- ADI Flash
- Pre-Flash TTL
- Manual Flash
"ADI Flash" - requires the use of an ADI capable lens (8-contacts - most of the newer SONY or SONY-compatible lenses). Flash intensity is derived from the distance data stream coming back from the autofucus/focus determination through the camera's logic. The amount of flash is then calculated through algorithms, determining flash intensity based on all the other inputs from the various sources (see the earlier chart). With such a wide array of inputs, you can see how dynamically these various inputs can affect the resultant capture.
"Pre-flash TTL" - allows the camera to make typical adjustments to the built-in flash; hot-shoe mounted or to a SONY-wireless flash. The SONY pre-flash transmits all this information to the external SONY flash unit, based on the algorithms used to set flash intensity. It is a flash signal that trips milliseconds before the full TTL flash burst goes off. (REMEMBER: The Pre-flash can trigger non-SONY flashes prematurely in the shot, so that these non-SONY flash sources do not time correctly with this setting and are set off before the camera shutter even opens.)
"Manual Flash" - you have manual control of the flash intensity... at the flash itself. The camera is reduced to just sending only a common trigger/sync pulse to set off the flash. There are no TTL adjustments or pre-flash to the flash unit. (Use this selection as your starting point, for troubleshooting.)
A clear understanding of these timing choices should be foremost in a studio setting, as this can cause some serious confusion and frustration, if not understood properly. Extensive experimentation is a great idea before committing to a electronic flash lighting solution.