Originally posted by Greenneck I wish I looked into clear aperture before dropping the cash for a da*16-50 for astro. That math works out to a worse astro performance rating than your 14mm for significantly more.
Now I have been debating the 14,16,20 and 24 Sam/Rokinon lenses for a few days and just can’t decide. If you broke your 14 today, which would you buy and why?
Your 16-50mm should/does have a higher clear aperture than a 14mm both at f2.8. The problem with the Da* 16-50 zoom is that wide open it probably suffers from heavy coma/astigmatism, whereas the Samyang 14mm f2.8 is excellent in this aspect, providing it is a good copy.
There is no way I'd have bought the DA* 16-50 for astro and I have a somewhat similar DA 20-40 f2.8-f4 Ltd for landscapes (superb lens but haven't tried it for astro as yet).
The way to go for astro is a K1 full frame with a Sigma 35mm f1.4, nearly the same FOV as a 24mm lens but with much greater clear aperture. This is the advantage of full frame or 645D or 645Z medium format as you can use longer focal lengths. All of this well beyond my budget!!!