Daniel,
For the budget you're talking, its going to be a hard push to get a telescope that will fully illuminate a 6x7 medium format camera. You might be able to pick up a second hand Takahashi FSQ or another scope with a sizeable field flattener, but you'd blow the budget in one go and have nothing to mount it on. Would suggest you search these forums to get an idea of a starting imaging rig and work upward from there. Clearly, your choices largely depend on what you want to achieve in astrophotography.
|