What are the best compact prime lenses for L-mount mirrorless cameras?

If you want the absolute smallest AF prime that doesnt feel like a toy, check out the Sigma 45mm f/2.8 DG DN Contemporary. It is basically the smallest autofocus lens you can get for the S5II that still feels professional. Tbh the Panasonic f1.8 primes are definitely compact but they are pretty chunky compared to this Sigma. Heres why it works for street stuff:

• It weighs almost nothing, like 215g.
• The build quality is all metal and has a manual aperture ring which is nice for street.
• AF is basically silent and works perfect with the S5II phase detection.
• You can usually find it for around 450 to 500 bucks. If you need something wider for those narrow Tokyo alleys, the Sigma 24mm f/3.5 DG DN Contemporary is even smaller physically, tho the aperture is a bit slower. Honestly for street shots, f/2.8 or f/3.5 is plenty during the day. Most people go for the Panasonic f/1.8 series because they want the bokeh, but if size is your main priority, these specific Sigma lenses are the way to go. Just dont expect them to be as small as Fujifilm or M-mount lenses because the L-mount itself is just physically huge. It is a solid compromise for the S5II.

If you want the absolute smallest AF lens that wont fall apart on you, the Sigma 17mm f/4 DG DN Contemporary is ridiculously tiny. I've tried many setups over the years and this one is about as small as it gets for L-mount while still being built like a tank. In my experience, Tokyo streets are tight and a wide angle is actually safer for capturing everything without having to step back into traffic. It has that metal build too, which I always recommend for travel because it just feels more reliable than the plastic stuff. The AF is fast enough to keep up with the S5II easily. You can usually find it for around 500 to 600 bucks. Honestly, dont go any cheaper or smaller or youll start losing that weather protection and build quality you need when you're far from home.

I hauled a heavy f2.8 zoom through Shinjuku once and it was a mistake... by day three, my shoulder was killing me. Small seems better for Japan. Do you prefer a wide or tight view tho? If wide works, the Sigma 24mm f/3.5 DG DN Contemporary is a decent option for $550.

• very light
• fast AF
• metal build Its much shorter than the Panasonic 1.8s.

Yeah, heavy gear in Shinjuku is the worst... I totally agree. I unfortunately bought a lens that was supposed to be tiny, but it felt way bulkier on my camera than I expected. It wasnt as good as the reviews made it out to be, especially for the price. Honestly, sticking to a strict budget is hard when everything compact seems kinda overpriced and underwhelming tho.