I have a bellows macro lens that is mounted on a pistol grip shutter release. I'd like to use that grip for taking pictures, but it has an old-style shutter release for film cameras, with a little metal wire that protrudes to trip the shutter. Are there adapters to convert this style of remote shutter release to modern shutter releases (I have a Canon 30D that uses Canon's 3-pin connector)?
The 30D remote shutter release is very simple - all you have to do to activate the shutter is short two pins - no arduino needed.
All you need is to take a microswitch (I used the reset button from an old computer for my DIY shutter release) and connect it the old shutter release cable so that the old cable presses the microswitch (sounds like a job for duct tape).
This page has the pinout for the shutter releases of a lot of cameras including the 30D
You have to connect one "leg" of the switch to the GND pin and the other to the SHUTTER pin (not important which leg goes to which pin) and you are done.
I've been told the small connectors used to connect all the switches and lights to PC motherboards fits the 30D connector, if you are not the kind of person that just happen to have computer parts around the house than any place that repairs computer will probably have "dead" computers they'll be happy to get rid of.
If you short GND to FOCUS it has the effect of an half press, short GND to SHUTTER for a full press, short FOCUS to SHUTTER and nothing happens (at least on my 550D).