What are the best compact prime lenses for the Panasonic S5 right now that wont break my back or my bank account? I finally picked up an S5 after years of shooting on my old Micro Four Thirds setup and while Im absolutely loving the full-frame look and that low light performance is just insane compared to what I was used to, the weight is starting to get to me. I have the 20-60mm kit lens and its fine for what it is, but its kind of slow and feels a bit plasticky plus it just makes the whole rig feel way bigger than I want for casual shooting. I'm looking for something tiny that I can just leave on the camera for street photography and maybe some family stuff.

I did some digging online and saw a lot of people talking about the Sigma I-series, specifically that 45mm f2.8. It looks super cool and retro with the aperture ring and everything but then I read some reviews saying the autofocus is kinda hunting on Panasonic bodies because of the whole DFD contrast system thing. Then there's the Panasonic 35mm f1.8 which everyone says is amazing and has fast focus, but it’s actually not that small? Like, it’s the same size as their 50 and 85 which is great for video gimbals I guess but for me it kind of defeats the purpose of compact.

Im heading to Tokyo next month for a two-week trip and I really want to keep my kit light so I can walk around all day without getting a sore neck. My budget is around 500 or 600 bucks tops so I cant go crazy buying those expensive Leica L-mount glass pieces even though they look gorgeous. Is there a pancake lens Im missing? Or should I just suck it up and get one of the Sigmas even if the AF isnt perfect? I really want something that makes the S5 feel more like a portable tool and less like a heavy work camera. Are there any hidden gems from brands like 7Artisans or should I stick to the ones with electronics...