If we would imagine a cluster of black holes at some reasonable distance from our solar system, and, at again some reasonable distance away [from that cluster], a nice bright star behind it, we would be unaware of that bright star being where it is. Now, if the light of that star would pass many another black hole, or other intense sources of gravity, that light may actually reach us via a detour, giving us the impression that there is a bright star out there, in the, for example, opposite direction from where it actually is, looking like being some one hundred times farther away than it actually is. I reckon therefore, that a possible magnification is the least of our problems when trying to figure out what is out there and where.