As we know Af lens don't have autofocus, it depends on DSLR body but D5100 didn't have autofocus motor.So, it is possible to use Af lens on D5100.
Will it be really to tough to focus manually.
My budget is tight, that's why i am going for AF not AF-S.
См. статью: Can i use Nikon AF 50mm f/1.8D Lens on Nikon D5100?