For professional headshots and fashion photography with your Sony a7C, prime lenses often provide superior sharpness and bokeh. TheSony 85mm f/1.4 G Master II is renowned for its exceptional portrait performance, delivering sharp images with beautiful background separation.

Alternatively, theSony 135mm f/1.8 G Master offers crisp resolution and creamy bokeh, making it a favorite among portrait photographers.

While the Sony 35mm f/1.4 GM is known for its sharpness, its wider focal length may not be ideal for traditional portraiture. Kit lenses like the 28-70mm offer versatility but may compromise on image quality compared to prime lenses. Therefore, prioritizing a high-quality prime lens would be beneficial for optimal image quality in your professional work.

Sigma 85mm f1.4 art.

tbh I always tell people to just stick with the high-end native Sony glass for professional work. Like, yeah, the third-party stuff is cheaper, but for pure reliability and basically guaranteed autofocus tracking, you cant really beat the official Sony pro-grade lines on an a7C body. I've had some weird issues with random disconnects or focus hunting on other brands before, idk if it was just my specific copy or what, but it definitely makes me nervous during a fashion shoot where you need it to hit every single time. Plus, the weather sealing on those top-tier Sony primes is just a lifesaver if you're shooting outdoors and it starts to drizzle, you know? I mean, you’re basically paying for that peace of mind that the lens won't flake out on you in the middle of a gig. I mean... well actually, the firmware support is usually way more consistent too. Just get any of the flagship Sony primes and you're set for years, right?

My buddy told me the exact same thing last week. Guess he was right lol.