If you have some legacy Pentax M42 screw mount lenses lying around they can be used on your Nikon with a Kood M42 adapter. I previously tried a different brand adapter and was disappointed and decided to try the Kood. It works very well with my S-M-C Takumars and yes I do get infinity focus. Of course they're manual focus but they're very sharp. My D2X meters perfectly in Av mode. There's a Man/Auto switch on the lenses so you can focus wide open and then stop down to your selected f stop. Here are a couple of examples taken with the S-M-C 85mm f/1.8 at ISO 100.