My whole thing with the range-finder is that it takes too long to use. Might have something to do with clouds, but I'd be sitting there trying to get a range on something for 20 seconds before I actually get a number, and then it disappears before I can even read it. And even if I do read it, it's instantly wrong because that ship is moving. And once more, once you know the grid size of the map, you can press M when a ship is spotted and get an approximate range.
So, for those of who do want working range-finders because of range achievements, we might consider making the range finder work on anything that's spotted, rather than just whatever's visible.
And yeah, get rid of those silly circles.