Oh man, i feel u… I built an L-mount “small body” kit for travel and the #1 lesson was: avoid the chunky f/1.4 primes unless you like wrist day lol.

In my experience, these balance great on Panasonic Lumix DC-S5 II / Sigma fp:
- Panasonic Lumix S 50mm f/1.8 — small-ish, fast AF, close focus is pretty decent, used prices are usually nice.
- Sigma 45mm f/2.8 DG DN Contemporary (L-Mount) — IMO the sweet spot for street. Tiny, good rendering, doesnt feel front-heavy.
- Zoom: Panasonic Lumix S 28-200mm f/4-7.1 Macro OIS — not “pro,” but for travel it’s SUPER practical and balances way better than the 24-70 bricks.

Just a heads up: the compact bodies can feel sketchy with heavy glass—use a wrist strap, seriously. cheers

For your situation, yeah… front-heavy L-mount is REAL, especially on fp/S5 II sized bodies. I’ve messed around with a few “small-ish” combos and these tend to keep handling sane:

1) Compact prime (35/50-ish)
- Sigma 45mm f/2.8 DG DN Contemporary (L-Mount)
- Pros: tiny, balances awesome, AF is solid, and close focus is surprisingly usable for food/details (not macro, but you’ll actually use it). Rendering is kinda “classic” too.
- Cons: f/2.8 means less subject separation vs f/1.8, and it’s not the sharpness king wide open (still totally fine).
- Panasonic Lumix S 35mm f/1.8 (L-Mount)
- Pros: small for what it is, fast AF, close focus is decent, and it’s just an easy street/travel focal length.
- Cons: longer barrel than you’d expect, so on the fp it can feel a bit nose-y vs the Sigma 45.

2) Small zoom that doesn’t ruin the vibe
- Panasonic Lumix S 20-60mm f/3.5-5.6 (L-Mount)
- Pros: honestly the “travel cheat code” — wide 20mm, very close focusing at the wide end, light enough that your wrist wont hate you.
- Cons: not a low-light beast, and background blur is… yeah, kinda limited.

If I had to pick: Sigma 45 + Panny 20-60 is a REALLY balanced kit. Good luck!

For your situation, I’d look at Sigma 35mm f/2 DG DN Contemporary (L-Mount) or Leica Summicron-SL 50mm f/2 ASPH (L-Mount) used… both feel way less nose-heavy than the fast glass, and AF’s been reliable for me. For a small zoom, Sigma 28-70mm f/2.8 DG DN Contemporary (L-Mount) is kinda the sweet spot—light, close-focus is decent, and it balances well on the fp. Just watch filter size/hoods, they add bulk fast lol

Same boat, watching this

So basically, everyone has covered the main native AF options like the Lumix primes and the Sigma 45mm, which are all solid. But if you’re a bit of a DIY enthusiast and wanna squeeze the most out of a compact setup, I'd honestly look at the Sigma 24mm f/3.5 DG DN Contemporary. It’s *stupidly* small and the close-focus is almost like a macro lens, which is perfect for those travel details. Another thing—since you're worried about handling and AF, I’d suggest doing your own "pro" tuning. Instead of sending gear off to a service center if things feel sluggish, get the Sigma USB Dock UD-11 and handle the firmware updates yourself. It sounds technical but it’s pretty easy and it really helps the AF stay snappy on those smaller bodies. Wait, I almost forgot—if you really wanna go tiny and don't mind a DIY approach to focusing, some old manual M-mount lenses with a slim adapter are actually the ultimate for street. It’s a bit of a different workflow than modern AF, but for travel, it makes the S5 II or fp feel like a totally different camera. Just a thought if you wanna keep the weight *really* low!