You shouldn't be able to get a clear shot at a deer in a northern hardwoods stand beyond 100 yards.Northern harwoods(not oak/hickory)have a lot of shade tolerant species that will grow(be it slower)under a mature manopy.Oak is different,Oak does not grow well under a mature canopy so you shouldn't expect good oak regeneration under a mature canopy.You have to remember though,only about 40% of our forests are oak/hickory.