David, It is easy to do so, and will deliver superior image quality to the Sony designed ZA lenses. Remeber that ZE/F are Zeiss's own lenses, so they are master of what they produce, rather than producing the Sony look.
There are of course several gems in the ZE/F lineup, and Zeiss are committed to completing the lineup and even adding several (three are confirmed) evern higher end lenses beginning this year. I expect these to be a big step toward their stellar cine line, they begin with a 55mm f1.4 Distagon in 2013, followed by an 85mm and an as yet undescribed wide angle.
Here is the Leitax page to look at for the new mount - it fits very easily, is entirely reversible, and you can fit a James Lao chip to obtain IBIS, highly recommended with the high res a99 sensor.
Voigtlander lens for Sony cameras
Write to David Llado at '
[email protected]' for details
The 21mm is the one to get of the super wides IMO, if the FL suits your work. I use a (perhaps better) version of this lens, the breakthrough Contax 21mm f2.8 from 1994, they go for about the same money.
Both are fabulous, and will shade the Sony ZA offerings substantially, and deliver a more authentic CZ image rendering. I have six Contax lenses on Leitax mounts and one Leica Summicron-R, it is very satisfying for any manual focus lens user.
Isn't the a99 something? I am amazed at the overall quality and effectiveness of the camera, the EVF and the sensor. What you see in the RX1 images, you will get as good or better with the 21mm on a99, as I found out on my trip this northern winter to Tibet.
Also, manual focus with magnification and peaking is a breeze, removing much of the uncertaintly seen with the a900. But be warned you will need to turn down your peaking level with the 21mm as the thing has such high contrast and deep DoF, the whole scene lights up! cheers, philip.