When compared with against rivals with similar focal lengths, the new lens ranks third, surprisingly, behind the original model and the Olympus M. Zuiko 17mm f1.8 although it outperforms the latter lens in overall image sharpness. In our practice shots, we have encountered no chromatic aberration with the Panasonic 20 mm 1.7, and the measurement values for chromatic aberration are also very low. What I wasn’t prepared for was that the image quality of this little E-P2 and 20 1.7 would surpass a Nikon D3s with a Nikon 50 1.8 (more on this later). I guess that right there is proof that a lens can make all of the difference in the world. When the lens arrived from B&H I opened the box and was pleased to see a lens pouch was included. Not that I ever use them really, but it’s a nice touch.

The lens is quite resistant to chromatic aberration, showing only slight magenta fringing in areas of high contrast in the corners of the image.Lens flare can cause some loss of contrast especially when shooting directly into bright light sources, while multiple ghosts of bright sources can manifest themselves as colored 'blobs' that get more defined the more you stop the lens down. Unveiled to the world just over a decade ago, the Panasonic Lumix G 20mm f/1.7 II Asph. lens has been around for a while and made many friends, but is it still a good buy for Micro Four Thirds users? Cons: in low light it hunts for focus, making it difficult to use on badly-lit events etc. when you still need to catch the instant action.

If you make a portrait on the street with a 50 mm lens on an SLR camera, then the subject might be intimidated by quite a big camera at a relatively short distance. With this little pancake lens, you have no problems with that. While the Panasonic 25mm F1.7 shows some longitudinal CA wide open, it becomes much less noticeable when you stop down a bit. Still, at 100%, you can certainly spot some purple and green fringing in the out-of-focus regions on the left side of this image, in the vines and stems. As I said the only flaw is the vignetting wide open at f/1.7 to around f/2. You can eliminate vignetting at f/4 or you can just correct it later in post processing (something very easy and 100% efficient with a good software). Image quality is almost flawless. Shoot at f/2.8 for sharpest images and also at f/4 for eliminating the vignetting. I may have said that the lens is sharper at f/2.8 but you'll be surprised at the image quality at f/1.7!I can actually confirm, the focus noise is still there. But it is definitely less noisy than before, I would say the noise has been reduced by half. Pure RAW score:This table shows the performance of this lens when the file is stored in the camera as a RAW file. This score approaches the intrinsic quality of the combination of lens and test camera. If you make use of Photoshop, Lightroom or SilkyPix for converting RAW files, then the RAW scores for chromatic aberration and distortion are the same as the jpg scores. Hi Steve, great review of the lens and what you say about size/weight compared to the D3s and 7D is true. I find myself wanting something smaller for street photography than my 5D Mk II.