Using the Voigtlander 35mm f1.4 Nokton Classic on a Panasonic GH1, the first thing you notice is how small it is, even with the Leica M > m4/3 adapter. Because this is such a small lens it can sometimes be a little tricky to focus. I find that I sometimes have trouble locating the focusing ring. However once you can cope with this, focusing is easier on m4/3 than on the Leica when the lens is wide open. On the M9 it can be difficult to locate a suitable focusing point to enable the rangefinder focusing, and even the slightest error can result in a mis-focused shot. The GH1, with its magnification aid, can make this easier.
I've included three shots at f/1.4. Clicking the images will link you to the Soundimageplus flickr page where there are full-size jpgs available to view. N.B. they are heavily jpg compressed.
Its a very nice lens for m4/3 with the proviso that it doesn't focus particularly closely. Its 70cm which is 2.3 feet, which is not very close at all. This is a problem with m-mount lenses in general, and is something to be borne in mind if you are considering using them. The 25mm f0.95 apparently focuses to 17cm which is just over 6 inches which is very useful indeed.
Because of the 2x crop factor of m4/3, the lens becomes a 70mm (35mm / Full frame) equivalent, and becomes a slightly longer standard lens or a short telephoto. 70mm lenses used to very popular with Hollywood movie makers for head shots. Many actors and actresses used to believe that they were very flattering & would often insist on them for their close ups. So it can be a useful lens for portraits - though remember the Voigtlander requires you to be over 2' away.
Like its performance on the Leica it produces sharp results and at some point in the future I'll do a longer review of it "in the field". It is a lens that many use on m4/3, as well as the 40mm f1.4. Because of their small size and relatively low cost, these are often peoples first venture into M-Mount. Indeed the 40mm was my first lens of this type.
If you want a lens of this focal length plus the speed its a good solution, and you wouldn't be disappointed with the results. Both Panasonic and Olympus seem reluctant to produce a fast "portrait" lens, so this lens could serve that purpose though it is a little on the short side. 35mm f1.4 lenses are usually very expensive. The Leica version is £3,300, and the Nikon is £1600 so this is a reasonably priced lens. It is also beautifully made and apart from the small size making focusing a little difficult (for me at least) nice to work with.
A very useful little lens for m4/3. I had some reservations about the Voigtlander 75mm f1.8 on m4/3 because of the focusing problems hand held. The 35mm f1.4 is somewhat easier to use in this regard and could be a very handy low light lens. Its small, light and produces good quality images. Its not as sharp wide open as the 20mm f1.7 lumix, but thats a different focal length. It is however very acceptable at f1.4 and being the equivalent of a 70mm lens and having the depth of field of a 35mm gives a little more latitude in focusing which is always useful in low light. People often talk about the disadvantages of the 4/3 sensor size in terms of depth of field. Personally I've always seen it as an advantage.