Just found this thread and ngl it makes me so frustrated thinking about the state of astro gear right now. Its like every time a new 'perfect' lens comes out, the price tag is just another slap in the face for people who actually want to go out and shoot. I've been down this rabbit hole with my own a7S III and honestly its ridiculous what we have to deal with. You spend a fortune and still end up pixel peeping because the corners aren't perfect or the stars look like little birds.

• The price hiking on wide glass is getting out of hand lately.
• Quality control feels like a total lottery even with top tier stuff.
• Lugging heavy gear up a mountain just to find out your copy has decentered elements is the absolute worst. I've actually been trying to rig up my own adapters and use older manual glass because the modern market just feels like such a scam sometimes. It drives me crazy that even with a beast of a camera, you still feel like you're fighting the hardware half the time...

Consider the Sony FE 14mm f/1.8 GM for its wide aperture and minimal coma. Alternatively, the Sigma 14mm f/1.8 Art offers excellent sharpness. For optimal results, use manual focus, set aperture to f/2.8, ISO 3200, and a shutter speed around 20 seconds.

I use the Rokinon 14mm f/2.8. Love it.

So I've been looking at the market for the a7S III lately and honestly that camera is such a low light beast you really wanna pair it with something that matches its potential but before I dive in are you looking for a super wide field of view for the Milky Way core or are you planning on doing more tracked shots with a bit more reach? Tbh the 14mm is great but there are some killer alternatives people often sleep on especially for balancing cost and performance. Here is how I see the top contenders right now:

• Sony FE 20mm f/1.8 G: This is basically the gold standard for value because it has almost zero coma and is way more versatile for daily use than a 14mm plus it is super light which is great if you are hiking to dark sky sites.
• Sigma 20mm f/1.4 DG DN Art: If you want to push that sensor this is the one to get because that f/1.4 aperture is massive for keeping ISO noise down and the corner sharpness is surprisingly good for a lens this fast.
• Sony FE 12-24mm f/2.8 GM: If you got the budget this zoom is kinda insane for the flexibility to frame compositions without swapping glass in the dark which is always a pain. What kind of budget are you working with though because that really changes the recommendation for a high end setup like this?

Seconded!

Sony FE 14mm f/1.8 GM is the best choice.