Pentax to nikon adapter?

I have a Nikon D3100 and my grandfather says he has "an old pentax 35mm slr" he did not say what model, but he did say that it has the bayonet lens mount. He says I can have all his lenses of I can find an adapter. If tried searching on eBay and other sites for one but I have no idea what to look for. Lol. Can someone tell me where I can find one, or does it even exist?

You need a Pentax K/Nikon adapter.

http://www.amazon.co.uk/...B003Y31A2W

Be warned, though;

The Nikon lens mount has a notoriously small diameter, so an adapted lens has to fit in front of it, rather than inside it.

To accommodate this, the lens needs a corrective glass element to allow infinity focus - this not only degrades image quality, but chops one stop off the lens' maximum aperture.

Any such lens won't allow the meter of the D3100 to work - I'm assuming you'll already know that you'll lose autofocus.

Many people don't think it's worth the hassle.

To reiterate, it's not worth the bother, but…

Grab the box of lenses anyway. Tell your grandpa you're buying a Pentax dSLR for them. An old and cheap 6MP iST DS should be enough but if you want Shake Reduction, go for a K200 instead.

Depending upon the Pentax lens mount, you will need to buy a used 35 mm Pentax that uses K-mount lenses and start enjoying shooting with film.

Using those lenses will help you decide what Nikkor lenses you will eventually want to buy for your fine D3100