Some context: I'm thinking about adding a standard zoom to my primarily prime-based kit. I shoot on an Olympus body, so Dual IS considerations are not a factor. The way I figure, if I want portability or widest aperture, I'll shoot using my primes. So, all other things being equal, it makes sense to me to prioritize focal length flexibility (the major advantage of zooms over primes) for my zoom. This would lead me to think the 12-60 would be the way to go. (for that matter the 12-100mm f/4 would probably be great, but it's a bridge too far IMO in both price and size/weight). My question: are all other things equal? E.g. sharpness, weather-sealing quality, build quality, etc. Essentially, I'm looking for a standard zoom with the widest possible focal length range that's never slower than f/4 and doesn't compromise on optical quality. Is that the 12-40 or the 12-60? Can anyone who's tried out both lenses speak to how they compare? Or for those who haven't tried both, why did you choose one over the other? Thanks.