I wish I had a straight 600mm. All lenses are Canon.
I also am considering a Meade schmidt Newtonian at f4. There are several tecniques for astrophotography to be used with a telescope.
I waited two hours for the moon to come up. I had more closer to the horizon, but atmospheric disturbances made the focus too soft as well as the exposure ended up being too short. Next time I will use asa 400.