Hi Mario
I used to do afocal imaging with my Sony DSCP100. I didn't have an adapter at the time, so I sat it on a tripod pointing into the EP of my 10" dob.
I would definitely recommend getting an adapter though, there are several available. Steve at MyAstroShop
sells some that look like they would do the job for you. If you're on a budget, the Vixen one (on the second page) looks good.
What sort of objects are you planning to image? Is your scope motor driven?
I'm just wondering why you'd want to have the shutter open.. for solar system objects it will be a short shutter, and i'd recommend using the self-timer to avoid camera shake.
Can your camera do manual mode? ie: set shutter speed?
Have a read of this article I wrote, which has a lot of hints and techniques for you.. it was designed for dobsonian photography but some of the hints will work just as well on any telescope.
Astrophotography with a dob