At the reunion/vacation last week I managed to borrow a Panasonic 20mm for awhile (probably could have borrowed it for a couple of hours, but I only stole 30 minutes of time with it). It was too brief a time to really “master” it, but I feel like it gave me enough use to get an idea for it. This is primarily going to be a comparison of it against the Olympus 17mm and Panasonic 14mm, in large part because I feel those two lenses are closest for a lot of reasons.
Panasonic 20mm, f/2.5, 1/400s, ISO200
On focus speed and noise: The lens is probably closest to the Olympus 17mm in this regard. The focus motor is just a tiny bit slower than the Olympus 17mm on the E-M5, which means in general it is still pretty fast. A rough subject comparison would put it at maybe half the focus speed of the Panasonic 14mm, which on the E-M5 is extremely fast, or maybe about 20% slower than the Olympus 17mm, which on the E-M5 is pretty decent. Noise wise, it is probably about 4-5dB louder than the Olympus 17mm, which means to the human ear at least, not quite twice the volume (the human ear does not have a linear response to sound, 3dB is a doubling of noise amplitude, but it takes about 6dB for the human ear/brain to preceive a doubling in sound volume). The 17mm you’d have a hard time hearing beyond arms length very quiet background noise, the Panasonic 20mm you could probably hear at about twice arms length with quiet background noise.
On size: The Panasonic 20mm is certainly a pancake, but it is a pretty big pancake. Its mostly because it is fat, not because it is long. I could pull up the numbers on it, but subjectively it is about 15-20% larger in diameter than the Olympus 17mm and maybe 10-15% thicker as well as about 1/4-1/3 again as heavy.
Panasonic 20mm, f/5, 1/1600s, ISo200
On image quality: Really nothing at all to complain about here. Wide open I did notice some vignetting, but it really just didn’t seem as bad to me as I have heard a few complain about. Nothing that you shouldn’t be able to correct in your favorite image editor if it bothered you. Distortion wasn’t noticable, but I didn’t test for that. Sharpness, well wide open it is very, very sharp in the center and things only get better as you stop down (not that they can get much better). In the corners, things are just a little soft wide open and they improve upon stopping down. Without “scientifically” testing it, the few pictures I took with it (around 50 or so) I’d guage that maximum subjective sharpness is reached by around f/2.8 and it doesn’t really seem to improve after that. By f/2.8 the corners are very sharp.
On banding: Aye, there’s the rub. I wanted to test the lens to see if I could produce noticable banding like a number of users have reported. I must, sadly, report that banding was present. Whether it is related to the specific camera body or the specific sample of Panasonic 20mm lens, the combo I was using did produce it. The various pictures I shot were at ISO200, 1600, 3200 and 6400. At base ISO nothing appeared. I didn’t test any inbetweens till ISO1600 so I can’t comment on those. I shot maybe half a dozen pictures at ISO1600 from properly exposed to a couple at around -2ev. One or two showed no banding at all, the others showed at least very minor banding, especially in shadows and especially if underexposed, when pixel peeping…but in general I’d hazzard to say none of it would be noticable in those few shots if you viewed them at 25% reproduction size or smaller and maybe even a little bigger if you cleaned up the shadow noise some more. At ISO3200 and 6400 the banding became more apparent, again especially when underexposed (I took about 10-12 pictures at 3200 and then at 6400). At ISO3200 again it was basically just in shadows and with a little noise reduction most shots at reproduction sizes of 25% or smaller probably wouldn’t be too noticable (at a guess an 8×10 probably wouldn’t show it unless you were getting nose grease on the print or a very rare poorly exposed shot that you raised shadows a lot). At ISO6400 it was much more intrusive on most of the shots and it would probably only not be noticable in a fairly small print or reproduction size, like maybe a 5×7 or around 10-15% reproduction size on the screen even with a little noise reduction. Deffinitely don’t try to raise the shadows/exposure level. Again, that would only be if you are looking carefully though.
Panasonic 20mm, f/5 , 1/800s, ISO200
That out of the way, I’d say the Panasonic 20mm is a very nice lens on the whole. I could wish for faster focusing, quieter focusing, deffinitely a fix for the noise banding, but at the end of the day, it delivers an f/1.7 apeture, is very sharp even wide open and is kind of a nice field of view. Even if the banding is never fixed on the E-M5, I think I’d like to pick one up some day. However, the perspective difference from 17mm is pretty minor, and I think for me 17mm and 25mm are better perspectives, most of the time. So, I’ll just yet again say I hope Olympus comes out with a small, good quality and inexpensive 25mm f/1.8 lens this fall like they are rumored too. I’d snap that up in a heart beat. If that doesn’t happen I am going to have to do a little soul searching on whether or not to get the Panasonic Leica 25mm f/1.4 or the Panasonic 20mm f/1.7 (even if the later is going to limit using higher ISOs too much, but it does give a stop and a half more light gathering than, say, the Olympus 17mm or Sigma 30mm meaning I could in theory reduce the ISO a stop and a half).