Sony Tamron lens, can it mount a Nikon?

I just got a Nikon and I got the standard kit lens. But I have a 70-300mm lens for my "a" series Sony. Do they sell something I can screw on to the lens and mount it to my Nikon D5100? If so can someone tell me what it's called or even better a link where to buy it?

I doubt it but if an adapter exists, there has to be an optical element in it to correct focusing to infinity. Optical quality will degrade highly though. Not advisable.

NO

Each camera company makes lenses specifically for their camera bodies and auto-focusing systems.

Just sell the Sony lens and buy a Nikkor AF-S 70-300 mm lens.

Adapters, when they are available, reduce the the shooting process to fully manual, lose a stop of lens aperture and some can't focus at infinity… Including in many cased requiring the user to use an external light meter (about $250) Any perceived savings by using an adapter is lost in all the jazzing around that has to be done to take a photo using a lens that is not compliant with the camera

There are almost no adapters for other mounts to Nikon, other than old 39mm screw mount stuff. Nikon uses a very narrow lens mount compared to just about everything else.

An adapter that would allow you to use the A mount lens on an F mount camera would cost as much as just buying the Nikon 75-300 G model. The A mount would need to have aperture control through the camera, along with a means of driving the autofocus. Your D5100 does not have a focus motor, which the A mount lens requires.

The least expensive lens in the same class that would be worth buying is the Sigma 70-300 f/4-5.6 APO model. The Nikon 75-300 G is not as good as the Sony, you would have to move up to the 75-300 ED model, if you can find one, and they cost more.