I was today trying to understand why the 20mm focal of the 20/1.7 seems to render very nice photographs. Outside of the quality of the lens build and design. There is just some about how it composes images I find. So I was looking into what the definition of what a Normal lens is mathematically and why it's typically 35mm (on a full frame equivalency with respect to focal length due to crop). I didn't realize the definition was based on the diagonal size of a 35mm frame. ie a 36x24 frame yield a length of 43.3mm (never really thought about it) so Normal (not wide or telezooms) is about 45mm and not 35. 35mm could be common due to some really good glass at the focal having been selected way back when and everyone got used to composing with it. So taking that into consideration..what's a NORMAL view on a 35mm shouldn't be the same on a CROP sensor by definition. On a m43 sensor of 17.3x13, yields a 21.6mm focal for NORMAL. Exactly where the 20mm/1.7 renders. Additionally, apply the 2x crop yields 42.8mm; pretty much equivalent to a 43.3mm full frame normal by definition which is expected. That might be why I don`t particularly care for the images taken with the 17mm prime lens but the 20 seems to be a sweet spot. I feel the crop effect is more pronounced for smaller focal lengths due to the compression effect and to get a similar `Feel` of a full frame 35mm, taking it a 20mm on a m43 might be more stylistically the same. So for me.. I consider the 20mm focal length the real normal on a m43 system vs. 17mm when attempting to achieve the same image of 35mm full frame image. Yes it will be a tighter composition but a more normal less compressed rendering. Curious what others think..