coincidentally I just got a rokinon 14/2.8 specifically for starscapes and went camping / shooting / timelapsing this past Saturday night at Algonquin provincial park. Unfortunately there was the full moon perigee that i think washed out the night sky despite being in a dark sky zone. the I'll post my results as soon as i've developed my lens correction profile.
I understand why people don't love the Rokinon, the focus scale is beyond pointless. This is my first plastic lens since i bought my first dslr 5 years ago that came with two crappy kit zooms, but it seems like a decent trade off in terms of weight and price. The hood shape wise is as good as can be without being in the FOV; the front element doesn't protude as much as i worried it would be; i was surprised there was no half aperature stops and the fricken lens cap is a pain to worry about when not on the lens.
i do like the weight, smoothness of the aperature & focusing rings and can't wait to shim the mount (calibrate the focus scale) and add a chip to it.
Somehow the Leitax conversion mount gives me perfect infinity on my 21mm ZF.2.
It is precisely the reason though why I didn't use the Rokinon 35mm F1.4 I had with me even though I could have used the extra stops. I had no idea where infinity was.
I suppose I should learn about stacking images and all that for astro but I'm just not that into it since I actually live in a place that is very counterproductive to this sort of photography.
Gotta love the IBIS when it works like you wish 
