Mate and I are trying to find a NSW/ACT TOPO map, prefer 1:20000 to run on OzExplorer. I'm not sure whether the NSW HEMA maps includes ACT. Any one out there with these maps or info on where to obtain (at best price) would be greatly appreciated.
Have a look at the GPS Australia forum. They have a very good set of 1:25,000 maps for free. They pass a DVD around but I dowloaded them from an FTP site and if you can work out the sheet numbers you want for ACT, you can just download them ones you want.
The standard map scale in Australia is 1:25,000 so go with them. Nobody makes 1:20,000 map. But in digital mapping, it is the combination of the scale and the scan resolution that matters and you should be looking at the scale in metres per pixel. Natmap 250k is about 31 metres per pixel and my 1:25k maps are 3 metres per pixel. My NSW 1:25k maps are 4.48 metres per pixel.
Here is a familiar bit of the ACT at 4.48 metres per pixel....: