Interested in Language
Do the following sentences read well?
Get close as 10 feet from it and you're dead.
Get as close as 10 feet from it and you're dead.
"Get as close as ten feet to it..." sounds better to me.
I agree with the previous two responses. You can also say "Get within ten feet of it and you're dead". "Within" would be taken to mean any distance from ten feet to zero inches!
Within ten feet sounds more natural to me.