What kind of lens is good for brilliant focusing?

I have a nikon D3100,
I'd love to get a better lens, I want one that would have brilliant focusing
Can anyone help me? X x:3

Macro lens.

A macro lens, my dad has got a sony alpha a400, he has 70mm sigma macro lens there 250 well thats what paid there brilliant tho

Depends on what you mean by brilliant focussing.

You can get a beta lens by goin 4 your choice

Most lenses these days have 'brilliant focusing', but a lens that has high contrast will APPEAR to be sharper particularly if the light is harsh, bright midday Sun for example.

The lenses with the highest contrast (and other optical advantages) are primes, lenses that don't zoom, have just one focal length. Pictures taken with wide range zooms will appear 'dull and lifeless' by comparison to the same scene shot with a prime, which is why people who want the highest possible quality images carry a bag full of primes.

For your camera, check out the 35mm AF-S lens from Nikon. It's not terribly expensive. I use the 35mm f/2.0 D lens (among others) and it is extremely sharp.

See especially:
and