I just tested my Zeiss/Contax 21mm F2.8 (the CY fully manual version made in Japan) and compared with the Panasonic 14-140 at matching focal lengths and from wide open to F11, printed full frame (down rezed in Photoshop) 8x10's and 200% blowups. Little difference. The Zeiss was sharp corner to corner, but to my surprise the 14-140 was as well. Obviously the Zeiss is faster, but lacks zoom and OIS. So not all 35mm wide angles are bad on the GH2.
I tried a Vivitar (Komine) 28mm f2.0. Almost no contrast and very soft when wide open, and when stopped down a couple of stops still easily beaten by the short end of the14-45mm Lumix. Avoid.
One of the sharpest lenses in my collection is the Sigma 24mm ultra wide II. The copy I have is AF, and I use a cheap adapter that has an aperture wheel. It is sharp to the edges even in full frame. For 28mm I use the Vivitar Close Focus SMS, they are hard to find in Pentax but you can sometimes find them in MD mount for a bit less money. Of course, there are pricier alternatives.
I've tried the Sigma 20, 24, 28, 30, and 50mm primes in Nikon and Four Thirds mounts. While they're a little soft wide-open for still photography, they're plenty sharp for HD video resolution. The Sigma 20, 24, and 28mm in Nikon mount have manual focus rings with hard stops at each end. making them very usable with follow-focus gears. The Sigma 30 and 50mm have HSM focus rings that lack hard stops. However, the 30mm has virtually no focus breathing and is very fast at f1.4.
The 28mm Takumar is only f/3.5, but it's really crazy sharp right at the start. The sharpest i've seen with the 20mm 1.7 pancake, really. Don't really know why it's so underated, cause i also have the 50mm SMC 1.4 and the 24mm 3.5 to compare with.
I have a Rokkor 24mm 2.8 VFC, and that beast is tack sharp from the start.
Had a 21 mm Konica but F4 - v sharp edge to edge - Lomo 28 F 2.5 is funky and cheap
Ive just been given an old OM 24mm 2.8 Olympus / Vivatar and for a freebie its pretty darn good! It was made by Cosina in either 1986 or 76 judging by the serial. :-)
So can the canon fd 20mm 2.8 be recommended on a gh2? I was offered it for little money...It is not the perfect 35mm equivalent, but almost...
I believe this theory (old lenses below 35mm performs badly in GH2) is completly wrong. Of course there are lenses better than others. And using the old lenses you need to stop down one fstop to get good sharpness, because m43 sensor enlarge the middle of the lens image and this increases imperfections.
@apefos thanks a lot.
I am just testing a Tokina RMC 17 f3.5 on the Lumix cameras. Resolution appears to be similar to Lumix 14 mm Pancake, but without digital sharpening. Seems to be pretty close to ideal for video with minor barrel distortion, but no color issues. Tokina RMC 24 f2.8 is not bad either. For both lenses contrast is slightly reduced at full aperture, but manageable.
Vivitar above appears to be nice. If the serial on Vivitar's starts with 37****, then they are supposedly the same lens as the Tokina RMC 24 f2.8. As a sidenote, when using lower contrast lenses, it is a good idea to try other Film Mode than Smooth or Nostalgic (Vibrant, for example) to capture the highest amount of hues.
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