Remote camera triggering
Canon RS-60E3 / Pentax CS-205 pinout
The cheaper Canon DSLRs, among other cameras, have a simple 2.5mm stereo jack socket for the remote shutter release, with a standard pin-out:
The pin-out diagram and circuit for the remote switchThe pin-out diagram and circuit for the remote switch
The pin-out diagram and circuit for the remote switch
The following cameras use this pinout and plug:
  • Canon EOS 300D, 350D, 400D, 500D, 550D, 600D, 1000D, 1100D, 30, 33, 50, 50E, 300V, 300, 500, 500N, 3000, 5000, IX and IX7
  • Contax SLR 645, N1, NX and N digital
  • Hasselblad: H, H1, H2, H2D and H1D
  • Pentax *istD, *istDL, *istDs, *ist, *istDL2, MZ-6, ZX-L, MZ-L, K100D, K110D, K10D, K20D, K200D and KM
  • Samsung GX 1L, GX 1S, GX-10 and GX-20
Note that despite having a 2.5mm jack socket, Panasonic/Lumix cameras use a 4-pole 2.5mm jack and a different pinout. Most other cameras use proprietary connectors, most easily obtained by cannibalising cheap e-bay remotes. Pinouts for a number of these are available at
Unfortunately, the behaviour of a the camera shutter is only tangentially related to the signal input at the remote release socket; see these measurements of shutter lag (typically tens to hundreds of milliseconds), and some estimates of minimum exposure time in bulb mode (typically 1/100th to 1 second).
Remote flash triggers
Most flashes (those using a standard hot-shoe or PC cord) are triggered by closing a normally-open momentary switch inside the camera. Unlike camera shutter relases, the lag time is typically sub-millisecond. The flash provides the power to this circuit, but the potential difference between the centre pin of the hot-shoe (positive) and the surrounding metal fitting (ground) is far from standardised. In particular, the this may be 200V or more in older flashes designed for mechanical cameras, easily enough to fry the solid-state switches in modern digital cameras. Most cameras accept a strobe voltage of up to 24V, with the exception of Canons, which are rated at 6V (but anecdotally accept somewhat more). Kevin Bjorke has a handy list of strobe voltages.

Tripod screw thread
The standard tripod screw thread for stills cameras is 1/4" Whitworth. The larger thread often used to attach tripod heads to tripods is 3/8" Whitworth.