I am getting a portrait lens for either my Nikon D5100 or Olympus E-PM2.
For APS-C, it would be Nikon AFS 85mm f1.8G which cost around $600 or less via import.
For m4/3, it would be Sigma 60mm f2.8 for around $240 locally.
Please note that m4/3 60mm = APS-C 90mm
1. Nikon f1.8 lens would give me much more bokeh than Sigma due to the larger aperture and sensor size/format.
2. Shooting with E-PM2 + Sigma 60mm would give me stabilised shot which is very important to me, although I can use a shorter shutter speed with the Nikon lens (due to f1.8) and thus can jolly freeze the subject more.
3. Nikon lens is around 2x the price of Sigma.
4. I will be able to carry two sets of camera systems (D5100 + Sigma17-50 f2.8 OS and E-PM2 + Sigma 60mm f2.8) and avoid switching lenses if I buy the Sigma lens.
Or is there any 3rd party lens for Nikon system that is around 85mm or 105 mm, is stabilised, f2.8 or larger aperturre and is affordable (i.e. $600 or less to import)?