Amyotte:
I have an 8"f6 Dob and a scopetronics setup for my digital camera. I am
able to take 1/30 second shots of say Jupiter and Saturn. Unfortunately I
do not have a guiding system to track so stacking multiple images becomes a
problem.

There are fantastic images taken by others where a 1000 images are stacked
and the detail is incredible.

I have tried to stack multiples of the same image with little luck in
obtaining anything but an over exposed image. A couple of image stacks may
bring out some detail. I understand that multiple images can reduce
background noise and grabbing a group of saved images during a window of
great seeing can also help.

For me to try stacking do I set the shutter speed to say 1/250 sec and
although the image, when dumped to the computer, is very faint would I then
stack 100 copies to grab the detail and increase the brightness?

Not sure if I have worded my question correctly but I am hoping someone will
know what I mean.

Generally speaking, "stacked" lunar and planetary images are not a
stack of photos from a digital camera (though they could be); they are
QT or AVI videos of a certain duration (i.e., a certain number of
frames) captured with a webcam and a computer. "Stacking" software such
as Registax or Keith's Image Stacker permits the imager to select the
best of the individual frames, align them, and combine ("stack") them
into a final image that is higher in quality than any of the individual
frames; it is often quite amazing how good the end result appears
compared to how poor the individual video frames appear.

Stacking individual images from a still digital camera also works. In
the case of a planet where rotation over a relatively short period of
time is an issue you would do well to take the images in as rapid a
succession as you can carefully do. It doesn't matter that you don't
have a guiding system, because you're going to visually put the
planetary image somewhere in the frame (accuracy isn't important so
long as you capture the entire planetary disc). The accurate alignment
will be done in software. The rule of thumb is the more frames the
better; Daniele Gasparri says that his recent image of Saturn was made
of 1,500 frames from a Philips webcam
http://www.marcofazzoli.com/danielegasparri/html_eng/saturn_050302.htm.
Nonetheless, you can make very good images with half a dozen
still-camera frames if they are focused and exposed with care -- and
with a decent sky and a bit of practice. You should be able to capture
Saturn or Jupiter with shutter speeds slower than 1/250, but I'm a bit
too lazy to calculate the minimum speed that you need with an unguided
'scope. Patient experimentation with note-taking as to what you did
during each imaging session is the key. After a successful session you
consult your notes and do the same thing at the next session. If that
session also succeeds, you have your technique and the rest is
gathering experiencing and refinement of the technique.

Davoud