Just figured this out by accident...
Get a ghost with a detector that corresponds to what you are looking for (spinmetal, helium filaments, or relic iron) and use you sniper as a kind of radar extender, I don't know how it works but it does, it should bring up all the little material circles in area, no matter how far away they are.
edit: confirmed by [b]Japhremel[/b] that it does indeed work on other planets.
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It works with all scopes, but yes the snipers are best because it seems dependent on your scopes zoom. And it also works on all of the planets.