Adding my two cents here because I love diving into the technical specs! Honestly, if you want to maximize your $600 budget, you seriously need to look at the Samyang AF 35mm f/1.8 FE. I was looking at the MTF charts on SonyAlphaBlog recently and the center resolution is just incredible for such a lightweight optic. It's way cheaper than the Sony native version, leaving you extra cash for travel! If you want a more premium feel, the Sigma 35mm f/2 DG DN Contemporary is a fantastic alternative. It has an all-metal build and a dedicated aperture ring which is amazing for tactile control. I always check the distortion and vignetting data on DXOMARK first, and tbh, the modern software corrections on the a7III handle 35mm distortion perfectly fine. 85mm is way too tight for Shinjuku alleys, so definitely go with a 35mm focal length!

Coming back to this... I used a 40mm in Osaka and it worked great. Honestly, the 85mm is kinda tough to use in those tiny ramen shops or crowded subways. A compact lens makes the a7III feel way less bulky when youre walking around.

• Sony FE 40mm f/2.5 G is around $598 and very sharp.
• Sony FE 50mm f/1.8 is usually $248 and a solid budget choice.

If you're heading to Tokyo soon, the Sony FE 35mm f/1.8 Wide-Angle Prime Lens is definitely the safer bet. Honestly, 85mm is way too tight for those narrow Shinjuku alleys and crowded spots. You'd be backing into people or stepping into the street just to get a decent shot of a building or a cool shop front. The 35mm is really versatile and the distortion isnt even that bad on a full-frame body like the a7III... mostly just around the edges if you're way too close. The Sony FE 85mm f/1.8 Portrait Lens is super sharp, but it's just not practical as a primary lens for a trip. Stick with the 35mm for now since it fits your $600 budget and is a reliable option that wont let you down. It basically handles everything from street shots to food photos. Lemme know if you need more help with the setup.

Honestly it drives me crazy how the lens market is lately. I am happy with my own setup now, but the path to get there was such a headache because prices are honestly ridiculous. You save up all this cash for a dream trip and then realize even basic glass is pushing your entire budget.

• blatant price hikes for minimal spec bumps
• quality control feels like a total lottery with decentering issues
• cheap plastic builds that dont inspire any confidence It really feels like a scam sometimes when companies expect us to pay premium prices for gear that might fail after a few months of heavy use. I am satisfied with the technical results once I finally find a good copy, but the constant worry about reliability and overpaying is just exhausting. I totally feel your pain on this, it is such a struggle.

Building on the earlier suggestion, I've spent a lot of time swapping between native Sony glass and third-party options like Sigma or Tamron. In my experience, it's not just about the focal length but how the brand actually handles colors and contrast. Over the years I've found that Sony's native lenses are beastly for autofocus speed, which you'll definitely want if you're chasing shots in a crowded subway station. Third-party stuff can be more hit or miss but often gives you more 'soul' for the money. I wanted to ask a couple things to help narrow down what you actually need:

• Are you planning to do a lot of video while you're there, or is this strictly for stills?
• Do you prefer a lens that's tack-sharp across the whole frame, or are you okay with some character (like vintage-style bokeh) if it saves you a few hundred bucks? I'd honestly recommend checking out the Philip Reeve blog or the Fred Miranda forums before you pull the trigger. Those guys do deep dives into how different brands compare in real-world street photography. It's a lifesaver when you're trying to make that $600 stretch as far as possible.