- Must be able to switch automatic focussing off
- Must be able to control exposure time, ISO sensitivity and lens aperture manually (there is an M setting on the dial)
- Should be able to save the images in RAW format rather than JPEG (which discards information)
- Could usefully be able to attach a remote trigger to avoid touching the shutter button
- Would be nice to be able to detach the lens (an SLR camera) to use different lenses or a telescope
+ You do need stacking software (free, from the Internet)
Another tip: if you keep a UV or skylight filter on your lens to protect it, take it off for astrophotography. Otherwise you are likely to get ghost images of stars due to reflections between the front of the lens and the filter. I once thought I had discovered a comet but it turned out to be a ghost reflection of a bright star. You learn from experience!