many of us love the gxr m mount, though truth be told, it is really not a very good low light performer. below is a link (because i just cant seem to get the hang of posting photos--my bad!) to some recent very difficult lighting portraits taken with the zeiss biotar 75/1.5--perhaps the best all around lens i ever used. the lens is so good it clearly outperforms the sensor in this situation, and i thought yielded some pretty nice results. there's additional explanation as well. hope they are interesting, and c&c is always welcome!
Lowlight Portraits with the Biotar 75
Lowlight Portraits with the Biotar 75