In terms of distance, an ant can see the sun, just like you can. Ants don't HAVE a focal distance, since they don't have a lens and retina arrangement, so the question requires dancing around. Each individual facet of the compound eye corresponds to a single pixel. That's not going to be a very detailed image, no matter what. Something like a dragonfly or horsefly, on the other hand, has tens of thousands of facets, giving much better resolution.
Ants are toward the low end of the scale in that regard, and some, in fact, are totally blind.
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