Originally posted by SteveB I did measure voltages on my K100D 's hotshoe a couple of years back. There was one pin that changed logic level when the shutter was half-pressed and it stayed on for about 20 seconds I think. If you used that to switch on a bright light then it would still be lit when the shutter fired, so a real flashgun would have to interpret other pins' signals to turn off the light before exposure takes place, but if you were using infra-red LEDs then there would be no need to turn them off before exposure and it would make for a very simple circuit.
At a guess, one transistor a resistor and an LED would do it, but of course you need a power source as well, I don't think there's anything substantial available on the hotshoe pins, so an external battery would be needed for the LED power.
Power source would not be a problem if I use an LED all I'll need is one or couple of CR2032 batteries, which would not take much space at all. One could start a business making this thing.
Originally posted by StarDust Flashes can be used as SB's only and that means with some simple code the flash sends info or something like that saying "hi I'm only an AF assist right now". That could be done.
Also IR assist??? There IR filters in front of the sensors. What we see is red light, nothing else.
my point and shoot sony cybershot does not have an IR filter, do DSLRs have them?