Originally posted by kman42 Hi, I'm looking for a budget ultra wide angle lens. Mostly for astrophotography and also general landscape shots. My research has lead me to these two. I realise the zenitar is a FE - I'm fine with that, as I shoot raw so I can either correct the distortion or leave it as an effect.
I'll by mounting on my K5ii which I understand will give an equivalent field of view of a 11-12mm rectilinear.
You've done your arithmetic incorrectly. On your K-5ii, with it's APSC sensor, the 14mm will be a "21mm-equivalent" and the 16mm will be a "24mm-equivalent", assuming comparison to a full-frame 35mm camera.
The 16mm is a "full-frame" fish eye on a 35mm camera. With an APSC camera only using the central portion of the image, distortion can be less obvious than you might expect, if framed appropriately.
I have neither of these specific lenses, so can't make any sort of comparison, but I do use a my Fujinon 16mm fish-eye on my APSC cameras occasionally with good results.
The difference between a 21mm and a 24mm on a 35mm camera is quite noticeable, so the same will be true between a 14mm and a 16mm on APSC. Only you can really decide an what you want/need, but, if you can, buy second-hand. That way, if you're not happy, you're more likely to recover most if not all of your initial outlay.
If you really want to go "ultra-wide" and don't mind the fish-eye effect, one of the old Peleng (or similar) 8mm (12mm-equivalent) full-circle fisheye lenses can give quite spectacular results for a good price
Good luck