Coming back to this... I totally get why you're hesitant about the Sigma's price. Honestly, for your situation, I would suggest looking at the Viltrox AF 56mm f/1.4 E. I've been using it for months on my own a6400 and I'm really happy with how it performs. It's usually well under your $350 limit, basically around $299 or less if you catch a sale.

The 56mm focal length is literally perfect for portraits on APS-C. It gives you that gorgeous compression that makes faces look way more natural than a 35mm would. I mean, the Viltrox AF 33mm f/1.4 E is great for "lifestyle" stuff, but for that creamy bokeh you're craving?? The 56mm wins every time.

One thing though—I'm always a bit cautious with third-party glass, so just make sure you update the lens firmware via the built-in USB port. It really helps with the autofocus stability on the a6400. I've had zero complaints once I did that!

Anyway, here is what I recommend:
* Viltrox AF 56mm f/1.4 E - This is the absolute best value for portraits right now imo.
* Viltrox AF 33mm f/1.4 E - A solid backup if you find 56mm too "zoomed in" for your backyard shots.
* Sigma 56mm f/1.4 DC DN Contemporary for Sony E - Seriously, keep an eye out for a used one. It is the gold standard if you can find a deal.

I'd stay away from the super cheap manual-only lenses like the Meike 50mm f/1.7 unless you have tons of patience... it's sooo easy to miss focus on friends and family when they're moving around. Stick with the Viltrox and you'll be stoked!! gl

Ok so, I went through this last year. I tried the Sony E 50mm f/1.8 OSS but:

- Slow DC motor
- Major hunting

Unfortunately, its NOT as good as expected... serious disappointment.

yo! i totally feel u on that kit lens struggle... it's basically impossible to get that nice bokeh with it. honestly, for portraits on ur a6400, a 50mm or 56mm is SO much better than a 35mm because of the focal compression. I actually bought the basic Sony fifty first but i was kinda disappointed tbh. The autofocus was literally hunting all the time in low light and it felt a bit dated compared to the camera's speed... not as good as expected.

Here's how I see the options:
- Sony fifty: cheapest, but the AF is sluggish iirc.
- Sigma 1.4 prime: literally the sharpest specs ever, but pricey.
- Viltrox lens: i think these are the best value lately?

I guess the third-party brands are actually reallyyy good now and fit ur budget. Ngl, the Sigma is worth saving for if u want that clinical sharpness, but basically any fast prime will be a huge upgrade over that kit lens. anyway, peace! 📸

Honestly, it's kind of wild how many options we have now for the a6400 compared to just a few years ago. Back then, you were basically stuck with the main name brands, but the market has shifted so much lately with these third-party manufacturers jumping in. From what I’ve seen doing my own research, the trade-offs usually come down to firmware support and how the lens actually communicates with Sony's autofocus system—some brands are super proactive with updates while others sort of leave you hanging. Before you decide, I’m curious about two things to narrow down the search. First, are you planning on doing any video at all, or is this strictly for stills? Some of these newer brands are great for photos but can be a bit noisy or "jumpy" during video AF. Also, do you have a preference for having a physical aperture ring on the lens? I’ve noticed some people really like that tactile feel, while others prefer just using the camera dials. That might help rule out half the brands right there (at least that's how I usually filter my searches).

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

I totally agree with what has been said about the older glass having some serious AF hunting issues. If youre looking for reliability, honestly the hardware is only half the battle these days. Since youre on a budget and looking at third party options, you really need to think about the DIY maintenance side of things, specifically firmware updates. Some of these newer brands basically require you to be ur own tech support to get the best performance out of the eye AF on the a6400. I have been shooting for years and I am always a bit cautious about jumping into a system without checking how easy it is to update the lens yourself at home. Before you pull the trigger, I have a couple of questions to help narrow it down:

• Are you comfortable connecting ur lens to a PC to run firmware updates, or do you need something that works perfectly 100 percent out of the box?
• Does the idea of buying used and doing ur own quality checks appeal to you, or are you strictly looking for brand new with a warranty? Keeping things up to date yourself can save a ton of money over professional servicing, but you gotta be okay with a bit of troubleshooting sometimes.

ngl i have been struggling with this exact same dilemma for my a6400 for months now. i keep diving into the technical teardowns and firmware update histories to see which budget glass actually holds up for a diy shooter, but i still havent found a clear winner. it is honestly so frustrating because every time i think i found the right specs, i find another reason to doubt it... still looking for a real answer myself.