I have tried the following camera with my scopes, they all work well
Canon SD790IS, Casio Ex-Z80, Pentax Optio M50, Samsung L700.
The commonality of them is that they all have 3-4x optical zoom. I have tried some camera with 12x zoom and there is always vignetting at the corner.
It seems 3x/4x zoom is the magical number to get a good results from digiscoping.