What is the difference between ADI Flash and TTL flash. I found a few articles on the subject.
Maxxum 7 TTL flash vs ADI flash system
"The ADI system helps when you have a reflective surface in the background. If you were to take a picture of someone in front of a window and you focused on the person, you might get a big reflection of the flash from the glass which would cause the camera to reduce the output of the flash leading to an under-exposure of the main subject. With ADI, the camera knows that you are focused on the person and will disregard the reflection from the glass. "
he pre-flash utelises the 'normal' 14 segment meter to evaluate the correct exposure rather than the 4 segment dedicated TTL flash meter. In theory this should produce more accuarate results. The ADI system gives extra feedback to help correct problems caused by excessively reflective surfaces in the picture.
By knowing the distance to subject, it is possible for the ADI sytem to calculate the correct flash output on its own but for some reason this only occurs when using the built-in flash. When using an accessory flash, the ADI is always used in conjunction with pre-flash.
Having said that, turning HSS off, setting bounce flash, using off-camera flash, rear curtain flash, multiple flashes or mirror lock-up cancels the ADI/Pre-flash and the whole thing reverts to TTL metering anyway.
So, if you use your flash as the main light source, on-camera, pointing straight at the subject, in conditions that may confuse the exposure system, then ADI can be useful as it 'throws a little extra into the mix' when the camera calculates the correct flash output.'
If someone out there in cyberspace can add something to this i would sure be appreciative of it. My new F58AM Sony flash came in and i have wondered the same thing.
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