Vintage lenses for Nikon D3100?

I want to buy a new lens for my D3100 camera. But I want to buy the old(vintage) manual ones to improve my knowledge of taking photos. So what do you think?

They will not meter on the D3100. And manual lenses seem to give less vibrant photos.

It's fine, but you can do the exact same things with modern lenses.

Don't bother… Just use your modern lenses, but turn off the autofocus.

D3100, 3200, 40, 60, will not work; since those cameras haven "shoot without lens attached" function. You can use manual focusing but you need a diaphragm electric control unit on it. Some adapter rings with a electronic simulator exist on e-bay. They tell the camera that a lens is attached. But, those af-confirm adapters exist only for Canon, Sony and OM, not for Nikon.

Most new Nikon lens have two settings. You can set them to manual focus. But be very sure it's set correctly, or you can damage the lens.

Back in the good old days film camera viewfinders had split rings and microprism collars to aid in manual focusing. The DSLR's don't. I think any gushing about the joys of manual focusing is only plausible for cameras that were well designed for it.

Agree with Dr. Iblis and Taylor. You can use your existing lense with autofocus turn off.
If you still want to buy, buy the 50mm 1.8.It does not have focusing motor, so you are forced to focus manually. And it also cheap.