I'm not too big on doing comparisons because I really don't like photographing the same scene under the same conditions with the same exposure just to look at differences, and I'm definitely not doing that here. Instead this is different scenes, different exposures, different days. First, the 17mm F/2.8 pancake after sunset looking vaguely towards the west before all the light died from the sky. This was taken on December 31 last year, my last photo of 2012. And this is the 17mm F/1.8 a little after sunup the other day, looking vaguely east so in each case the sun is in front of me but off to one side out of the image. Finally, another shot with the F/1.8 that has been posted elsewhere. Late afternoon with rain impending, sun behind me this time. All relatively dark images, all processed to emphasise the sky and get as much dramatic effect there as possible. I hesitate to draw strong conclusions because the shot with the F/2.8 was made under darker conditions with a little less contrast in the scene but these shots illustrate my general feel that the F/1.8 produces images which hold more contrast and grab my attention more. I've always liked the colour rendition of the F/2.8 lens but while there's some nice subtle tonal gradation in the sky in the first shot, it doesn't quite deliver the drama in the sky that I can get from the F/1.8 and I think the F/1.8 also does nice colour rendition but in a slightly different way. Make what you will of it, but the F/1.8 seems to have been glued to the E-M5 since I got it.