Thanks for that advice, I did not know that there was such a thing as an opto-scr.
I'm pretty sure my flash doesn't go above 300v, my multimeter says 160, I've just heard rumors they could go up to 400, so perhaps the TLP372 could work, but I am leaning towards theVO4257. One thing I don't know for sure is the current requirement of the flash, since my multimeter doesn't trigger the flash when measuring the voltage, it must not let through enough current. So the higher the capable current the better.
One thing that would help big time is can anyone help explain exactly what variables I should be looking for on a datasheet? I mean, I wish it was more simple like max input voltage, and max output voltage, and speed. But instead there are so many more complex terms, such as input always contains "reverse voltage", "forward current", "breakdown voltage", "collector emitter voltage" and many other cryptic terms. Which one simply means the input voltage? And when you try to figure out the amount it can pass through the output, they are always full of cryptic terms like "off state voltage", "continuous power dissipation", "breakdown voltage", "dark current", "isolation voltage", "rms on state current", and many others, how to I simply figure out how much voltage and current can pass? Also the speed, on occasion I think I find speed listed on datasheets, usually in "us" microseconds, but many times I don't find it at all. I'm not too picky about speed, but as long as its within the microsecond range it should be fine, but I'd still like to know, and can't always find it.
If anyone could simplify which are the important fields to look at, it would really help in being able to figure this stuff out on my own. I've tried looking up datasheet reading tutorials before without much luck.