ahalpert
Major Contributor
The Sigma's AF should be better with its focusing motors, the Samyang 1.4's are only so-so compared to other options. I had the 35/85 and switched to the FE 1.8's, which are pretty much flawless AF-wise, really fast and accurate, and stays locked on to your subject really well, bonus they're really small and gimbal friendly too. The partial stop loss is worth the trade for size/IQ and better AF. The Sammy's have a warm cast too, the Sony's are more neutral.
I was shooting with the GM 2.8 trinity, which are great but really bulky and I try to have my entire kit fit in one carry-on size backpack. I moved to the Tamrons and the 12-24 to shed weight and be more gimbal friendly. The AF with the Tamrons are really good, occasionally they have a slight hesitation before locking onto your subject, but that's rare and usually something really low contrast - at least on the a7III. I've had zero issues with the a7s3, tap the LCD and it sticks to everything. They track subjects really well and IQ is GM level. You do give up range and controls on the lens like the custom buttons and the AF/MF switch (the one I wish they had) compared to the 24-70's and 70-200's. But for a 2.8 zoom. But they're so small/light with such great performance, its everything you want a zoom to be. The 70-180 also extends, but its so tiny compared to the GM and AF/IQ is so good, its something I can live with for the convenience of the zoom.
The 12-24 is a really fun lens. I got it because I use the 16-35 in the 16-20mm range mostly and wanted to go a little wider, so I was able to shed weight and go a lot wider LOL! The filter issue is its only drawback IMO. But you can stuff 77mm filters into the hood without contacting the front element, so you don't have to go the chop route to avoid those ridiculous 150mm filters. There's a great thread on Fred Miranda about that, linked below. I just recently invested in a bunch of 100mm filters for landscape photography and I don't want to eat the loss selling those and buying more expensive 150mm filters. There's an adapter that a 100mm filter holder will clamp onto, but as mentioned you have to chop down the two longer petals to be even with the shorter ones. Yikes.
https://www.fredmiranda.com/forum/topic/1503152/0
All in all, every one of my lenses are just fantastic on the a7s3, the real time tracking blows me away every time I'm shooting. I'm doing some traveling in the next couple weeks to the Grand Canyon and I'll be shooting a lot while putting the camera through its paces. So far I've just been shooting standard profile with 10-bit to keep things quick and easy.
Cheers
Chris
You had the samyang 35/85? Supposedly the firmware has improved the AF. Although the 50 is a total lost cause. They also have new, small f/1.8 35, 45, 75 with even better AF. But I like the color and rendering of the 35/85 and I wanted maximum sensitivity/minimum DOF. I think that with the right settings (faster transition, less responsive to switching subjects) I can get good AF results from them. If not, I have until the end of January to return them.
Interestingly, it seems like maybe AF is much slower in low-light when shooting the standard profile than it is when shooting a log profile. Do you find that as well?