Some silly thought hit me on the head again, so I thought to pose a question here to see if there are any answers around:
For very long exposure photography such as star trials or techniques that involve painting with light, Bulb setting is often necessary, but a cable release or remote is often recommended to trigger the shutter release and subsequently close the shutter when the exposure is over. But what if we have neither of these accessories?
As an example, I switch the camera to self-timer mode and let this trigger the shutter release for a bulb exposure. Then, to finish the exposure, would it be possible for me to cover the lens opening very carefully with a black card, before stopping the exposure by pressing the shutter release button, without causing camera shake in the final image?
Any thoughts are appreciated. If this is not going to work, then I might consider finding a cable release.