10-25-2016, 05:00 AM
If "astro" appears in the intended usage list, I would stay away from AF lenses, if I were you. None of them has a mechanical stop at ∞ . I would try to get my hands on an Irix lens just because of some of their features, try it and if it fulfills my needs, use it and don't care about other offers. If I were you, but I'm not, so for me AF is also important as I trust it more (in LV) than manual focus. PDAF on Nikon - at least at mine - works less reliable, wide open and off center, so it clearly is a case for "better LV, if it has to be wide open".