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| Re: wireless TTL and metering mode |
For product shots, my preference would be manual exposure and manual flash power, with both parameters established by a flash meter. Once your lights are in place, I would assume that you don't move them much -- if at all -- during a session, so metering once and then leaving everything alone would make for a fast and efficient work flow.
The problem with TTL metering is that the camera doesn't know if a part if black, white, gray, bronze, steel, etc., so it will try to make everything look middle gray...probably not what you want. By using a flash meter, you wouldn't need to make multiple test shots; because you'd bve measuring the light falling on the subject rather than the light reflecting from it, you meter once and you're done.
If you do still want to use TTL metering, the way to prevent blown highlights is to spot-meter the highlight: take a shot with the lights positioned, check the LCD to see what's blown, put the metering circle over that spot, trigger flash exposure lock, recompose for the desired framing, then take the shot. It's faster than it sounds, once you've done it a few times, but still much less efficient than taking an incident reading.
The problem will be that while your highlight area will now be exposed for medium tone, your shadows and mid-tones will likely be underexposed and so you'll still have to fiddle with flash exposure compensation.
My final suggestion, if you haven't already done so, is to get the book Light -- Science and Magic. It has many sections devoted to how to light objects to avoid unwanted reflections and specular highlights...and also why some can be a good thing for revealing shape and texture.