So I have two questions regarding the use of double cable releases.
The first inquiry is just addressing the need for them in the first place. I have a Canon EF (not the lenses, the old body) & AE-1P and I use them with an Auto-Bellows FL. When I've done this, I simply use the stop down metering. So what's the advantage of using a double cable release? I just don't get it.
AND secondly, this is actually what I came here to ask, and although it doesn't relate specifically to macro photography, I figured you guys would know better than most.... I want to use a double cable release to fire two cameras at once (or in close succession) for stereo photography. It appears that most of the cables have one line that is shorter than the other to permit stopping down first, then shutter, right? So how long is the delay? For static subjects, a large delay wouldn't be a problem but I'd like to be able to take pseudo-action shots. Would faster "plunging" permit a shorter dealy?