What's the best lens for astrophotography with a Sony a7SIII?

Question

Considering the Sony a7SIII's low-light capabilities, which lens offers optimal astrophotography performance, especially for capturing sharp stars and minimizing distortion and coma? Are wider-angle lenses like a 12-16mm or 20mm f/1.4, or even faster lenses like a 50mm f/1.1, ideal for Milky Way shots? Do the Sony 20mm f/1.8G or Sigma 20mm f/1.4 DG DN lenses offer a good balance of performance and budget? What focal length and aperture combination best suits celestial object photography with this camera?

RobertGap · Accepted Answer

Honestly, before I jump in with a specific pick, I really need to know what you are actually planning to do. Are you mostly looking for those huge wide-angle Milky Way landscapes, or are you thinking about getting a tracker for deep space stuff? Knowing your REAL budget limit would help too because budget means different things to everyone. I always tell people to look at reliability first. It is SO frustrating to drive two hours into the dark just to have a cheap lens have focusing issues or weird coma because the elements shifted. Here are some solid, cost-effective options that wont let you down:

Check out the Sony FE 28mm f/2. It is basically a hidden gem. It is very affordable, light, and surprisingly sturdy for the price.

The Tamron 20mm f/2.8 Di III OSD M1:2 is another great one. It is not the fastest lens out there, but since you have the a7SIII, you can just basically bump your ISO and it performs reliably in the cold.

Look into the used market for a Tokina FiRIN 20mm f/2 FE. The build quality is like a tank and you can find them for a steal these days. Reliability is key when you are out in the middle of nowhere at 2 AM. Let me know your setup plans and I can give better advice.

LowellgeExoda · Answer

Honestly, when I first started trying to shoot the stars with my a7SIII, I was super worried about spending over a thousand dollars on a lens I might only use once or twice a month. I ended up looking at things that were a bit more affordable because I didnt want to risk too much money right away. > Are wider-angle lenses like a 12-16mm or 20mm f/1.4, or even faster lenses like a 50mm f/1.1, ideal for Milky Way shots? From what I have learned so far - and I am still very much a beginner - the 50mm can be really tricky. I found that wider lenses are much safer for getting the whole Milky Way in the frame without much effort. With a 50mm, the stars start to blur into lines really fast unless you have an expensive tracking mount, which just adds more cost and stuff to carry around. I ended up looking at the Samyang 24mm f/1.8 AF FE because it has a special button that helps you lock focus on the stars automatically. It really helped my confidence because I was always scared of getting home and finding all my photos were blurry. A few things I keep in mind now are:

the price of the lens versus how often you actually use it

how heavy it is for hiking out to dark sky spots

if it has a way to help you find focus in the dark But yeah, basically I think staying wider is better for starting out so you dont have to worry as much about the math of star trailing. Plus, you can find some really good deals on used ones if you are trying to be careful with your budget like I am.

Pinebaby · Answer

I totally agree with RobertGap on the reliability front. Honestly, when youre miles away from civilization in the middle of the night, the last thing you want is equipment that might fail or has a loose mount. For the a7SIII, I always tell people to prioritize build quality over just having the fastest aperture. Having a lens with internal focusing and decent weather sealing makes a huge difference when the dew starts hitting or the temp drops... its just safer to go with something that has a proven track record for holding up in the field.