Been using the OM-D E-M5 with the Panasonic 12-35mm f/2.8 Pro and 35-100 f/2.8 Pro lense for a little bit. These are amazing lenses. Accorinding to photozone.de, because of defraction, this lense is actually sharpest at f/4 and declines significantly at f/5.6 (this is the defraction effect which occurs much earlier than with other lenses). Also because the lense has lots of native distortion, the edge and border sharpness aren't super. So at wide open the statistics are:
- 12mm, best at f/4, center at 3100 lw/ph (wow!) but border at 2350 and edge at 2200 lw/ph or about 10.5MP.
- 20mm, the best resolution is actually at f/2.8 of 3000 lwph center and border at 2375 and extreme corner at 2200
The new 12-40 f/2.8 at photoreview.com.au, it is jpeg with peak sharpness of 2750lw/ph at 25mm center at f/4.5 and 2675. For effective resolution of 11MP which is pretty amazing for a 16MP sensor with JPEG. The RAW resolution shows that the top resolution is at ISO 200 with RAW center at 2900 (?!) and edge at 2750 for 12MP effective.