I am still searching for a lens for shooting stars at night from the aircraft. I bought a Zeiss Distagon T* 28mm f2 (identical to the K series 28mm f 2.0) partly for this purpose. The main issue with that lens is its weight and length, the slightest turbulence exaggerates any movement. Camera is mounted on a Gorillapod. The K 28mm f3. 5 fares much better, and is far less prone to coma, but is not fast enough really. I use it at f4. So ideally I want a 28mm lens that's sharp across the (full) frame at f2. 8, not prone to coma, and lightweight. Shooting at less than f2. 8 appears to not be practical due to shooting through an inch of glass, I can't get everything in focus (I have tried it with various 50mm and 55mm lenses) I am only interested in manual focus lenses.
Any recommendations?