I've been looking over the time travellers companion again, specifically the bit about how clairvoyance works for the scanner. The distances given ranging from 5m up to 1AU depending on resolve only seem to work if you treat it as the central point range. That is the scanner can't see 5m rather you can put the point from which the scanner is looking anywhere up to 5m from the TARDIS's outer shell. Said point can be in front, behind, above, below and angled in any direction. After which it obeys the normal rules of viewpoints able to zoom in or out and give different visual modes but if there's a forest in the way you can't see through the trees.