Will a Vivitar 70-150mm fit a Nikon D3000?

Yes or no question.

Only if the lens has a Nikon F mount. Vivitar makes lenses for many different cameras, so it will have to be one made for a Nikon.

Also, see if the lens has it's own autofocus motor. Many lenses do not.

The entry-level Nikon cameras such as the D3000 do not have a focus motor in the camera body. Advanced Nikon cameras (D90 and above) do have a focus motor.

So unless the lens has it's own focus motor (and I'm guessing it doesn't), you won't be able to autofocus it with your camera. But you can still use manual focus.

If and only if the vivitar lens is made for Nikon cameras, otherwise no

Here is an outline answer to your question. You may wish to research further the subject of using old lenses on new cameras -- it is a rather daunting subject.

This lens and many other manual-focus lenses were made for 35mm film cameras, probably back in the 1970's, possibly the 1980's.

Both the lens and all those film cameras are now out of production.

[ The name "Vivitar" does not mean to photography in the 2010's, what it meant to photography in the 1970's. For starters, read here…

http://en.wikipedia.org/...ki/Vivitar ]

Vivitar made different versions of the 70-150mm -- They made a version to fit Canon SLRs, a version to fit Nikon SLRs, a version to fit Minolta SLRs, a version to fit Pentax SLRs, etc.

The version that they made for Canon film SLRs will NOT fit modern Canon DSLRs.

However, the version that they made for Nikon film SLRs can still be mounted to modern Nikon DSLRs. But it will not autofocus, and you will have to investigate questions regarding aperature control and metering.

Unless you really want to do this, it is far more straightforward / practical / productive to mount modern Nikon AF-S autofocus lenses on your modern D3000.

Either way, have fun!