Adapter for Nikon d40 to mount a Cosina 75-300mm Macro lens?

I bought a Super Cosina Macro lens 75-300mm at a yard sale (didn't have my camera on hand to test the fit), & I've searched ebay for adapters that might allow the lens to be mounted to my Nikon d40. Minimal knowledge when it comes to adapters & mounting other lens brands.

You will have to figure out what mount it has on it. Know anybody that has a Pentax, or Nikon, or Sony? Then look for an adapter.

There's a problem here.

Although Cosina produced cameras in Pentax K-mount, they also made lenses in other mounts towards the end, so you might have to work out which camera it was made to fit to start with.

In any case, you'll lose both autofocus and metering on your D40, and the adapter will need a corrective element - which degrades image quality - so you'll really have to ask yourself if it's worth the effort.

It isn't the sensible way to go… Adapters bring all sorts of problems for example you might lose metering on your camera and would have to shoot blind or use an external exposure meter…

Adapters (for me) just aren't worth my time or money… And the chances are you'll agree after spending some more of yours.

The best thing to do is to stick with Nikon mount lenses… If you are in doubt 'leave it out'… You should have kept your money in your wallet.

You would need to take the lens to a reputable camera store or very knowledgeable friend, to find out what mount the lens has. I know I had some version of that lens on my old Canon AL-1 in the early 80's, so they were made in Canon FD mount as well as the others mentioned already.

After that, use it for a paperweight or something, because it really isn't going to be useful on your camera, no matter what mount it has.

Not worth the trouble / costs. And any adapter will downgrade quality.

Bring the lens and camera to a camera shop and let them identify the lens mount. From there you would know what adapter to buy. If they have it, you're lucky. Take note however that you will be using the lens in full manual mode without the help of the lightmeter. It's really not worth the bother especially if the adapter costs far much more than the lens itself.