A:AnswerThe best option would probably be to have the 35mm slides scanned. Seeing that will be a full frame 90mm lens on a APS-C sensor the lens will act more like a 137mm lens. The crop down factor only occurs if you are using a APS-C lens on a full frame sensor.
A:AnswerHi there! Yes, this 90mm macro lens will work great with your NEX-5, however, there will be some bearable restrictions when you use it with your camera. Those restrictions will not affect the output of your shots. Kindly check this link below for more information when you use this lens with your NEX5: http://support.d-imaging.sony.co.jp/www/cscs/accessories/compatibility.php?area=gb&lang=en&mdl=NEX-5&cat=8 Regards, -Mark