voigtlander 35mm f1.2 aspherical ii with nex 6

FWIW, the Speed Booster plus a pancake version of the Nikon 50mm f/1.8 AIS is the smallest and lightest 35mm f/1.2 you can get.  For the combination the weight is 414 grams and the length from the front of the lens barrel to the NEX flange surface of the Speed Booster is just over 50mm.  By comparison, the CV 35/1.2 II alone is 471 grams (57 grams heavier), and you would have to add the weight of an M-NEX adapter to that.  More interesting for you is that the  50/1.8 pancake Nikkor + SB combo is a full 20mm shorter than the CV 35/1.2 plus an M-NEX adapter (~50mm vs 70.6mm)

BTW, when you add the SB to a 50mm lens the combination is a true 35mm lens (actually 35.5mm).  When you combine the SB with an f/1.8 lens it is reported in metadata as f/1.3, but this is rounded up from f/1.26, which is the actual value for an "f/1.2" lens (2^(1/3)).

You may also be interested to look at some of the 50/1.8 + SB = 35/1.26 sample photos taken by Vivek Iyer over at GetDPI:  http://www.getdpi.com/forum/sony/43130-speed-booster-nex-4.html .

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J. Brian Caldwell www.caldwellphotographic.com