Late to the party but I gotta chime in because I learned this the hard way at a shoot in Milwaukee last year. I brought an old HSM lens thinking it would be fine but the pulse-y focus hunting was a total nightmare on my Lumix. Like someone mentioned, you really gotta watch out for those older DSLR ports because they just dont play nice with mirrorless tracking. If you're doing a wedding, focus speed is everything when the bride is walking down the aisle. I've used both the 35mm and 50mm DG DN versions and there is definitely a clear difference in how they feel on the S5II.

• Sigma 35mm f1.4 DG DN Art for L-Mount: This one is super sharp and way lighter than the old version. It uses a stepping motor which is quiet but it might feel just a tiny bit slower than the newest stuff if you're really pushing it during fast movement.
• Sigma 50mm f1.4 DG DN Art for L-Mount: This is the one you want. It has the HLA (High-response Linear Actuator) motor. Honestly, the autofocus is basically instant. I used it for a reception dance floor and it didn't miss a single beat even in dim light.
• Sigma 85mm f1.4 DG DN Art for L-Mount: For those ceremony close-ups, this thing is a beast. The bokeh is creamy but be careful because it's still a chunk of glass to lug around all day. Just make sure you check the box for those DG DN letters. If it says DG HSM on the side, just put it back. You dont want that clunky adapter barrel built onto the back of your lens when you're trying to keep a low profile. The HLA motors in the newer 50mm are legit a game changer for the L-mount phase detect system... it feels way more native than the older designs.

Be careful with adapted glass. Id stick with the Sigma 85mm f1.4 DG DN Art for those ceremony shots. You can grab a used one for under 900 bucks if you look.

> some art lenses seem to be older dslr designs be careful with those. stick strictly to the dg dn glass like the Sigma 35mm f/1.4 DG DN Art for L-Mount or focus will hunt like crazy during the vows.