Sigma 14mm f/1.8 DG HSM Art full frame lens

introduction

14mm f/1.8 ultra wide full frame lens in various mounts
announced Feb 2017, available May 2017
Sigma can optionally fit a rear mounted gel filter holder (FHR-11 filter holder) for around $US80

https://www.dpreview.com/articles/1717621214/astrophotography-with-the-sigma-14mm-f1-8-art-lens
- lots of vignetting wide open but the gradient is soft and coma is reasonably well controlled but bat wing shaped at the edges
- does have lens flare issues with bright light sources such as a full moon
- a reasonable choice for ultra wide angle astrophotography or aurora shots where the additional aperture would allow shorter exposure times
https://fstoppers.com/gear/astrophotography-sigma-14mm-f18-dg-hsm-art-lens-and-coma-183601
- see comments section regarding coma issues
youtube: 14mm f/1.4 vs Rokinon 14mm lenses for astro
- much better star shapes than the Sigma 20mm and 24mm f/1.4 lenses
- not as sharp in corners as the manual focus only smaller, lighter, cheaper (half the price), Rokinon 14mm f/2.4
- the manual focus Rokinon 14mm f/2.8 is far cheaper, smaller, lighter but does have much more vignetting, much poorer build quality and optical consistency between lenses, and over time with vibrations such as driving on gravel roads, tends to be subject to lens de-centering causing softness of image quality
Youtube: 14mm f/1.8 for astro
- perhaps the best 14mm astro lens, minimal coma which is gone by f/2.8
https://www.camerastuffreview.com/en/sigma-lens-review/review-sigma-14mm-f-1-8-art-mc11
- 1.75EV vignetting wide open and 1EV at f/4
- sharpest at f/8 (f/5.6 in the centre)
- 3% barrel distortion