@gameb As I said earlier, it's parfocal. At least, I think so. Correct me if I'm wrong :-)

You can test any zoom lens by zooming in to the max FL, Shift the lens's AF to M or manual, take a picture. Then pull out the zoom at the widest FL, also at widest aperture, take the picture. Go to your PC or MAC and download the images. If your image is in focus at the max FL as well as it's widest FL, then your lens is parfocal.

I actually got to mount this lens on my GH2 the other day, but the shots are just from inside the camera shop, and not exactly my most cinematic work. The lens felt good in the hand, and compared to most panny lenses the focus ring felt good, but I tested the Nokton 25mm F.095 lens this day ( I know it's apples and oranges ), and I am finding it harder and harder to enjoy panny focus rings even on the nicer lenses. Focus seemed smooth but I had a bit of trouble dialing it in.. granted it was my first try, and I am not exactly the most experienced focus puller. Also despite knowing better I kept trying to adjust the aperture X D

@mee Its so hard to judge the lens if you only upload a 720p file

Wow, thanks!

I just returned my sample of the 12-35 to the dealer. According to the reviews published after the lens announcement, distortion at 12mm was supposed to be half as much as on the Olympus 2.0/12 which I own. I am using a 12mm lens for architecture photos and video. Unfortunately the distortion of the new pana zoom turned out to be quite similar to the olympus. The Olympus gives me one more stop of light, lower vignetting and a much higher edge resolution. For outdoor run and gun shooting I already have the cheap 14-42 lens which resolutions wise is good enough for video. For indoor shooting f 2.8 is often not enough. Hence I decided to return the 12-35. I can confirm that the lens is regulated electronically. Whether the lens is parfocal or not I am not sure, but since it is not possible to make a smooth zoom with constant illumination while filming it does not matter anyhow since there are autofocus and focus expansion if needed. If Panasonic had considered to build a f 2.0 lens with a slightly larger long end, for example 50mm, at a higher prize and at the size of the 14-140mm lens, I would have kept the lens. Panasonic's mft sensors are just not light sensitive enough for 2.8 zooms.

I am using the GH2. The distortion is not very high for either lens, I was just hoping that the Panasonic 12-35 would be even lower. No surprise that it isn't since I am comparing a zoom with a prime lens. However I wonder how the various reviews came up with a lower distortion % for the zoom.

I am shooting raw and the software I use is apple aperture which I think is autocorrecting the distortion since it does on the 20/1.7. And doesn't the video mode auto correct distortion, too? I could see the same low but noticeable amount of distortion there. Straight lines at the edges of frames distort about equally with both lenses at medium distances of about 3 to 8 meters. At a distance of 50cm the zoom at 12mm seemed to distort even more than the olympus prime. But this is not my usual shooting scenario anyhow.

In my experience neither the 14-42 nor the 14-140 zoom have zero distortion at their widest setting, neither in photo or video mode. Both lenses have the latest lens firmware and both lenses distort equally on both GH2 bodies I own. All reviews of these lenses that measure distortion in photo mode state a moderate amount of distortion as well. The 12-35 lens exhibits a noticeable amount of distortion at 12mm as well. The 20/1.7 is measured with much lower distortion and I can confirm that I see no distortion when using this lens in video mode or photo raw mode. ephotozine measured a distortion of 0.543% at 12mm for the Panasonic zoom and 1.12% for the Olympus prime. So the distortion of the zoom should be exactly half, but with my copy it wasn't. I checked for firmware updates for the zoom but could not find any. My copy had the shiny finish with the ugly purple cast. I don't know how ephotozine and other reviewers measure distortion, maybe this kind of variation is normal. The 12mm Oly was tested on a G3, the 12-35 Pana was tested on a GF3. Maybe the GH2 has different correction algorithms than the other two cameras. What matters to me is that on the camera I use I could see no noticeable improvement in 12mm distortion, so I decided for the Olympus prime since it is cheaper and faster. For other users the 12-35 zoom with 2.8 might be a perfect allround lens. It all depends on what one needs.

I assume you are right. In comparison with most APS-C lenses the distortion of Panasonic lenses is very low, and that seems to be good enough. There are probably not that many people who shoot architecture on m43. And correcting distortion to 0% would take away some focal length. For photos I can correct the Olympus 12mm distortion in post, just not for video.

Lens is available at Amazon now

http://www.amazon.com/gp/offer-listing/B00843ERMW/ref=dp_olp_new?ie=UTF8&condition=new

"If Panasonic had considered to build a f 2.0 lens with a slightly larger long end, for example 50mm, at a higher prize and at the size of the 14-140mm lens, I would have kept the lens.'"

LOL!! UH, yeah, that is not going to happen. As I mentioned in another thread, 2.8 is nearly as fast as it gets on a zoom. Get real. Expecting Panasonic to produce an f2 for less than $10k is NEVER GOING TO HAPPEN. The fastest motion picture zooms are around f2.2 . And zooms are used all the time on features and television.

Ok, NOT GOING TO HAPPEN! :-)

One day Gh3 with 12-35 kit would be $1K...