Hyper Prime Lenses

These are 'super' wide lenses that are made for ultra low light photography ... their f-stop hover around the f1.0 range, Besides being quite rare (many are out of production) and a challenge on the wallet for many, you'd wonder how challenging it is to focus manually at such a shallow DOF.

There are two great reviews on one such lens, which is a new production, called the Noktor 50mm f0.95 (!) - http://www.slrmagic.com/ (p/s: take their product survey and select the camera mount you want them to make.)

Lens Reviews:

http://www.stevehuffphoto.com/2010/03/03/the-noktor-50-f0-95-lens-review-diary/

http://philipbloom.net/2010/03/10/review-of-noktor-f0-95-hyperprime-50mm-lens-for-micro-four-thirds/

Currently this lens works on these cameras without the need for any adaptor:
Panasonic: Lumix DMC-G1, DMC-G2, DMC-G3, DMC-G10, DMC-GH1, DMC-GH2, DMC-GF1, DMC-GF2, AF-100, AF-101, AF-102, and AF-103
Olympus: PEN E-P1, PEN E-P2, PEN E-PL1, and PEN E-PL2
Sony: NEX-3, NEX-5, NEX-VG10, and NEX-FS100