Well first look side by side just another tank of a lens!!! Then if used for Astro Milky Way and on the fastest camera for astro the a7S 1.4 A=10.00s D=20.01s A7Sii and A7Siii A=10.03s D=20.06s The difference in SS between 1.8 A = 10.47 D= 20.95 and 1.4 is A=10.3 D=20.06 So basically f/1.4 is 10s to 20s f/1.8 is 10s to 20s. and a while back using the A7S and a 16mm f/4 lens A=11.49s and D=22.98s or even a 12mm f/2.8 A=13.64s D=27.28. and for grins the 500 rule a while back was more than 30s for no star elongation and minimum comas. So what’s the new really a bigger lens like the Sigma 14mm f1.8 where you had star elongation and bad commas in upper corners and needed to shoot at 2.8 or even 4 to have good stars, I know I still have one and have not sold because I did not what someone to get the problem.
You get to use a lower ISO with the default SS. Light is Light at night with either SS or f/ or ISO adjusted and with a Sony with the correct setting of 0.0 meter mode you get a daylight bright with stars above even at the darkest of places.
As far a filters you need a holder for the 12-24 and the 14 but yes you can use the rear of lens Haida Clear Night filter. Just info any of the Sony lenses will be sharp near sand/shells and far buildings/ships at night where as the Sigma was blurry near and far, even a astro milky way youtuber mentioned and showed it.
Further you can use the APS-C E 10-18mm f/4 OSS (15-27mm) lens at 12mm -18mm (18 if you remove the light shield) if you want a very small lens to carry out somewhere if use at say 10s to 20s you will get pinpoint stars also.
My guess is Sony will have the 14mm f/1.4 soon and maybe a small 12mm 1.8. But while you wait just do some night time panos to get that wide look with just two images.
The sad thing is with either the 12 or 14mm you get a straight MW across the image and the image you will want is the MW ARC when doing a 200 degree panorama.
Ok if you still want to use in daytime the ultrawide is not about getting everything in the image but is about a close subject with a landscape story behind in the background but need to use f/8 or if you want the bokeh bulbs yes a 1.4 but again bokeh is about the focus point of using the small square on the subject.
And for further info for a super wide lens the Voigtlander 10mm f/5.6 is most excellent for that pano look in 3:2 if very close to the edge of say Horseshoe Canyon for getting the water below and the mountains on the far off horizon all in perfect focus and without loosing camera and pano gear over the side on a windy day! The 10mm f/5.6 is also good for Milky way shots if setting are set right.
Brian has most of this info in his many books he wrote back in the A7 model heydays always great info even today and I am blessed to have found them on a bookstore shelf some time ago.