I'd prefer a wide angle zoom or a tele zoom over a standard zoom. Usually a standard zoom isn't known for the best image quality.

Thanks @matt_gh2 for your feedback. Yah I was starting to think the same too. Just stick with my fix primes especially as I have both GH2 and GH3 now. Can just use the two cameras and frame with two different primes.

@matt_gh2 can you please report on the nikon 17-55 f2.8. If I understand well you can't control the aperture or this lens except you use an adapter that has aperture rings, correct? Like you I am in the market for zoom lens preferably a constant for narrative and some live event preferably a fixed f-stop. I was considering the tokina 28-70 at-x pro 1 but review says the focus ring is too tight. Then the Nikon 17-35 but covers less focal range. So I am interested to hear you thought about the 17-55 assuming that you still have it and have being using it for a while.

Found some time today to test my recent acquisition, the 28 to 85mm zoom, against some Contax Zeiss primes and thought I should share.

@ 28 against the slower 28mm 2.8 prime: Center resolution about the same, the zoom is bit less contrasty WO. The 28mm has traces of CA in corners, zoom has obvious CA, which is not improving much @ 5.6. Corner sharpness and contrast when both are @ 5.6 is remarkable, about on par, but @ 5.6 the contrast of the prime in center is definitely better than the zoom. The prime seems to have some minimal field curvature on changing the aperture (which is not rare for a wide that is well-balanced when open).

@ 35mm against the slower 35mm 2.8 prime (I didn't afford the 1.4): Both WO center is about the same, corner sharpness impressive, nearly the same, but some more CA and less contrast again in the zoom. The prime is not completely free of CA, but it's minimal. Center contrast improved @ 5.6, nearly on par, CA still visible. My 35 seems to be a tad weaker than my 28.

@ 50mm against the 50mm 1.7 (a very sharp lens!) The zoom is a tad sharper in the corners against the prime @ 1.7, but @ 2.8 the prime overtakes the zoom and kills it at 5.6, but it's my sharpest 50mm of them all, even better than the Planar 1.4 or the Rokkor PG, which are already analytical.

@ 85mm against the 85mm 2.8 (not the Planar 1.4): WO the zoom is considerably softer, while on par in CA – both minimal, @ 5.6 the zoom is improving considerably and nearly touches the prime.

General observations on the zoom: The zoom is generally improving regarding CA when going towards the long end, but it's also getting softer in contrast. Bokeh is very nice, no hard edges and minimal deformation in the corners. Go for MM to avoid Ninja blades, though. Zeiss is cheating a bit on both ends, the zoom is neither as long as the 85 nor as wide as the 28 primes. Color not quite the same, zoom seems to be a bit warmer than all my primes (more glass?).

Verdict (quite personal one): This is a very impressive zoom, I did massive pixel peeping to spot the differences and it's true that it's very close to these primes. I'm sure it leaves many weaker primes in the dust. OTOH it's not constant aperture and has a one-touch zoom. It is parfocal if you manage to keep it straight when zooming, but I'd rather consider it a variable prime in practical use. Even if my zoom tube is still stiff compared to other one-touch constructions I held, it slides if tilted up or down. While the mechanical construction is on excellent Zeiss level, this is caused by massive weight. It weighs a bit more than any three primes I could pick from the above (slower) ones and it needs a huge filter diameter and the filter rotates. I feel like I'm going to sell it again…

my "perfect" lens vote would have to go to the sigma 30mm it has it's pros and cons, but the good outweighs the bad IMO it has a pretty nice balance on the camera (unlike a voightlander) also it is very easy to see when it's in focus without having monitors and what not it's also somewhat affordable. has a great looking flare in sunny shots and a has a nice "cine" look at 1/40

the only 2 negatives is having to have an adapter with manual aperture ($80 on eBay from china)

Tip for the cheap adapters: you can slide a knife into the middle of each of the prongs that hold the lens in and expand them. The adapter will be solid as a rock after that. No need to pay for the expensive one unless you need a reliable tripod mount, or if you can't get proper infinity focus.

The camera mount itself will bow with heavy/long lenses and FF. Lens support is a must if you want to work professionally with this combination.

While electronic lenses of today have inherent shift when a FF is pressed against them, older lenses of good build shift the problem to a weak adapter or the camera mount itself.

Since the Novoflex is the best build money can buy, I'd only be concerned about the camera mount. Not so much it's precision when new, but if it lasts when stressed by a heavy lens. A long one (physically long) in particular, plus whip pans or shaky rides on transportation etc. will truly endanger your camera mount. Don't nail me on it, but anything beyond half a kilogram should be treated with respect.

What do you mean by "too heavy" ?

You can always get a lens support. Or get an adapter with a tripod support and hang the GH2 on it.

I've used Nikkor 18-55 f/3,5-5,6 and it was awfully difficult to focus it manually. For Nikkor 2,8 you need G-Nikkor adapter as well and stop it down a bit for really good IQ, just the same procedure like for any other Nikkor lens (except maybe for the 85mm f/1,4)

What about Olympus 12-60? I also need good sharp lens for undemanding shooting, and this Oly seems ok, cheaper, than nikon 17-55, lighter, wider range... Does anybody have some experience with this lens and gh2?