Depends what format it's being made fore, Sony don't make film cameras, 30mm on the Sony SLR's would be the digital equivalent of a 50mm macro lens on 35mm.

Macro lenses come in various forms and it really depends what's being photographed, some are longer than a standard lens 80/90mm, others 50/60mm, while for more extreme close up they can be shorter still 28mm/40mm, any shorter and they tend to be called Micro lenses. I've used an 8mm Micro lens on a Pentax for scientific work.

Ian