I started looking for an UWA lens (something in the mid-teens), particularly for doing milky way shots. Learning that you get trails with too long of exposure, I figured I'd try and find the largest aperture possible. After searching endlessly, I seem to notice a trend that there aren't lenses less than ~24mm, and particularly in the teens, that have f-stops less than 2.8.
Am I crazy? If not, then is there some technical reason as to why? (the f-stop part, not me being crazy)
Edit to mention I'm shooting a Canon 6D.