Hey! I’ve been using the a7S III for a while now, and honestly, you can’t go wrong with either, but there are some technical trade-offs to consider. I’m super happy with how my setup performs lately, so here's what I recommend:

* Sony FE 24-70mm f/2.8 GM II: This is the gold standard for video AF. Those XD linear motors are no joke—they track eyes even in dim event lighting perfectly. Having that extra 4mm on the wide end is a lifesaver for handheld work in tight spaces.
* Tamron 28-75mm f/2.8 Di III VXD G2: Seriously impressive for the price. It's much lighter, which your wrists will thank you for during long handheld shoots. The AF is great, though maybe a hair less "sticky" than native glass in low light.

Neither has built-in OSS, but the IBIS on the a7S III handles them both well. I'd go Sony if you have the budget... iirc it just feels a bit more robust for pro work. Hope this helps!

In my experience, I've spent years hauling gear to dark event venues, and honestly, the Sony FE 24-70mm f/2.8 GM II is the king for video AF. It's noticeably faster and quieter when tracking subjects compared to the Tamron 28-75mm f/2.8 Di III VXD G2. The Tamron is amazing for the price, but the Sony's active stabilization support is a lifesaver for handheld work on the Sony a7S III.

TL;DR: Go Sony for the best AF and stabilization; Tamron if you want to save cash without losing much quality.

> how do they compare for video autofocus?

For your situation, I would suggest the Sony FE 24-70mm f/2.8 GM II over the Tamron 28-75mm f/2.8 Di III VXD G2. The Sony's four XD linear motors are just more reliable for professional handheld tracking, honestly.

Hmm, I've had a different experience with the standard 24-70mm range. Everyone is pointing you toward the Sony FE 24-70mm f/2.8 GM II, which is technically a beast, but if you're doing handheld video and low-light events, I'd actually suggest a different approach for safety and reliability.

1. Respectfully, I'd consider another option: the Sony FE 16-35mm f/2.8 GM II. If you're shooting handheld, that wider focal length is way more forgiving for micro-jitters, especially on the Sony a7S III's sensor.
2. From a safety-first perspective, the Sony FE 24-105mm f/4 G OSS is actually my go-to for events. Even though it's an f/4, the built-in Optical SteadyShot (OSS) combined with the body's IBIS gives you a much more stable shot than the unstabilized GM II.

I totally get the love for the fast f/2.8 aperture, but in dark venues, I’ve found that missed focus or shaky footage is a bigger risk than a bit of ISO noise—which the a7S III handles like a champ anyway! Anyway, back to your question, if you're dead set on the 24-70mm range, the Sony is safer for professional work because those XD linear motors are just more reliable for long-term tracking. I've seen some third-party lenses lose connection during firmware updates, which is a nightmare mid-gig. Stick with native glass for the peace of mind! Hope this helps!

Bump - same question here

Finally someone says it. Ive been thinking this for a while but wasnt sure.

Interested in this too

honestly im dealing with this exact same headache right now and it is so frustrating. i tried some diy rig setups with older adapted glass to avoid spending big, but unfortunately the video af was just not as good as expected for handheld work. been searching for an answer for like three months and every time i think i have it figured out, i just find more issues... still stuck. tl;dr: i have the same problem and still havent found a zoom lens that actually hits all the marks for the Sony a7S III.

To add to the point above: I've spent years putting these lenses through the ringer and everyone is pretty much on the money about the Sony FE 24-70mm f/2.8 GM II being the top pick. Technically speaking, there are a few big reasons why it wins for video shooters specifically.

• Focus Breathing: The Sony is designed for the a7S III breathing compensation feature. The Tamron 28-75mm f/2.8 Di III VXD G2 is sharp, but you'll see the frame shift when racking focus.
• Motor Speed: Those four XD linear motors in the Sony aren't just for show. They handle the heavy lifting during 4K 120p tracking way smoother than the Tamron's VXD setup.
• Control: Having a de-clickable aperture ring is huge for low-light events where you need to ride the exposure without those annoying clicks showing up in your audio. I've tried many combos over the years and honestly, the native glass just integrates better with the phase-detection. If your budget allows, go for the GM II. It is a workhorse that wont let you down when the lights go low... let me know if you need help with the custom button setup too.

Wait really?? Thats actually super helpful. I always thought it was the other way around.