In reply to The Lemming:
Wait until the moon has gone, if there is any lingering high cloud, even if very thin, it will light up the sky and dramatically reduce the contrast in the image.
If the milky way is clear enough to see with the naked eye then your photos stand a fighting chance. If you can't see the milky way by eye you need darker skies.
Do you want to capture any foreground in your image or just the sky? If you want both then one exposure or the star movement will make stacking the images a problem. You would probably need to make a composite image to make that work.
If just the sky then I think take many shorter exposures, say 10-20 seconds.I think that will be short enough on the widest field of view to minimise significant star trails. Experiment. If the images look too bright, the sky might not be dark enough.
You should be able to see the milky way in a single exposure, but it doesn't matter if it is a bit dark as the stacking process will allow you to bring it out later. If the sky is dark enough to allow really clear images, then try stopping the lens down from 2.8 as it will probably be sharper.
The advantage you get from taking many short exposures then stacking them is that you can make a high dynamic range image with smoothed noise which you can then manipulate the histogram (using a paint program) to bring out the milky way. If you just have a single image and you try to stretch the histogram I think it will look quite speckly due to the noise being exaggerated.
The key is to experiment. Go with a plan and record your settings and see what works. You had some good moon images before, try a similar process
