>>2577694>Any further feedback on this would be great.Any adapter that has corrective optics in it (which is mandatory to put a K-mount lens on an F-mount camera) is going to eat optical quality, and generally quite a lot of it. If you built those adapters to the standards of a nice Nikon or Pentax piece of glass (like a 1x teleconverter), it'd probably work pretty well. It would also cost $500. Nobody who wants to adapt lenses will pay that much, so decent adapters don't get made.
So what are your options? Well, one, you can just deal with it, and use your 50/1.4 only on your film camera. Two, if you shoot with your Pentax and decide you want some fast primes, Nikon of course sells them. A 50/1.8G is only somewhere around $200 used. (your D3100 can't autofocus the older D lenses) Three, you could trade in your Nikon and switch systems. A Pentax DSLR will work fine with SMC-M lenses (though you need to hit a button to do stop-down metering). You can get a K-30 with it's kit lens for $350. That's a bargain for what that camera can do, but whether the hassle and expense of doing that is worth it to you to use your new lens is debatable.
