When I arrived home from work today my 20/1.7 lens was waiting for me. I tried it on my G1; I really love the image quality; I was shooting indoors at night under dim artificial lighting at ISO200 and was able to get shutter speeds of 1/50 or so with the lens wide open. Very nice.
The only downer for me is that, compared to the 14-45 lens, the 20mm doesn't focus as well. It makes noise, for one; that's not such a bad thing, as its not that loud, and the manual for the lens implies that the drive mechanism for this lens is different from the others. The problem is that the lens is actually slow to focus. And it hunts and overshoots -- not all that often, but enough to know that this ain't the 14-45 lens, who's operation is totally transparent to the user.
I'm hoping that out in the street this lens will perform okay, but my initial impressions are that this lens is less than stellar in operation, compared to the 14-45 lens. That's the price you pay for a fast, compact pancake lens. I will be happy overall with the 20, I'm almost certain, since I don't have any other legacy lens of this focal length and speed. Manually focusing, if I have to, is a viable option in order to have the compactness, image quality and speed this lens offers. It just ain't the 14-45.
~Joe
