Jim Thompson said:
[snip]
For general use - i.e. fast *and* slow shutter speeds - you might
consider pneumatics.
I used to have an el cheapo remote shutter release (bought in Tokyo back
in the 60's) that I used with an SLR. Piston screwed onto the shutter;
10-12 ft. soft rubber tubing connected piston to a hand operated squeeze
bulb. This low-tech thing was so gentle that I retired the handsome
cable release I had been using.
This shutter button has no threaded insert like you usually find on
better film cameras. So I'm studying my tripod to see how I can rig
it up.
I had a similar requirement a couple of years ago and ended up doing
that, i.e improvising a gadget attached to tripod.
It's a scandal that modern cameras heave neither an electronic socket
to operate the shutter nor even a screw thread for mounting a simple
release. I spent ages getting this thing working. Rather than my Sony
DSC-1, I used an old Olympus Zoom auto-focus. Felt less nervous about
leaving that outside overnight.
My aim was to photograph whatever was coming through a hole dug below
my garden fence. I thought it might be foxes. So I had to arrange to
press and release the button. Eventually, after a lot of
experimenting, I designed a unit inside a small plastic case. I
connected an old-style cable at one end to a solenoid plunger in the
case, and its other end was just on top of the button. The mechanics
proved a greater challenge than the electronics for me. But after
virtually constructing Hubble single-handed I imagine you'll get it
sorted a lot faster <g>.
My sensors were micro-switches attached to lightweight, camouflaged
board, and provided the trigger. All crude, temporary stuff. Circuit
ensured camera wouldn't get re-triggered within 5 seconds or so, while
motor wound film on for next shot. A mono powered the solenoid driver.
Power supplies were via mains. A *long* extension cord. And we get
rain here, so weather-proofing was another challenge.
The trickiest aspect was powering the solenoid. Extensive
trial and error to get reliable action. The surplus component I had
available was rated at 24V and my first approach was to use a
multiplier and largish capacitor to power it from the 6V supply I was
using to emulate the camera's battery. But eventually that proved
inadequate, so I added a 29V line.
Block diagram, circuit and a few photos:
http://www.terrypin.dial.pipex.com/Images/cameraaddon.gif
http://www.terrypin.dial.pipex.com/Images/Camera-addon.gif
http://www.terrypin.dial.pipex.com/Images/CameraAddOnImages.jpg
Bottom line: three cats, two squirrels - no foxes!