On Tuesday, 21 July 2015 13:51:05 UTC+2, Mike Collins wrote:

You can use the timer instead of cable release. Many compact cameras now
have bluetoth remote capability.A selfie stick can be used as a remote and
is very cheap

Thanks, but timers are too crude for taking snaps at precise but opportune moments of best centring, object framing and freedom from vibration.
Neither of my compact digital cameras has Bluetooth capability nor any form of remote shutter release.
No doubt one could easily arrange something mechanical like a suitable lever.
Or even use a solenoid to depress the shutter button via a hand-held switch or even a bell push.
I have simply relied on holding the camera to the eyepiece.
Sometimes with, and sometimes without, a centring adapter tube for the nose of the camera lens.