TL;DR: The Sigma 20mm f/1.4 is unbeatable for landscapes. I took the Sigma 20mm f/1.4 DG DN Art to Iceland last year and the weather sealing held up perfectly. Be careful with weight though. Honestly, the rendering is stellar, but you lose that Leica 3D pop. If you want extreme wide angles for those dramatic vistas, definitely look into that prime instead of a heavy zoom.

Honestly, if you are heading to Iceland, dont blow your entire budget on a single lens. You really need to think about the environment there too. Salt spray and wind are brutal. I would suggest picking up the Sigma 35mm f/1.2 DG DN Art instead of going for the native Leica option. You get that incredible speed for those dark Icelandic nights, and the sharpness is honestly ridiculous for the price. If you really need a zoom and are worried about the cost of that 24-90, try looking at the Sigma 28-70mm f/2.8 DG DN Contemporary. It is so much lighter than the massive Art glass, which is a lifesaver when you are hiking around waterfalls and glaciers all day. Just be careful with swapping lenses in the wind; dust is everywhere. If you can live without the Leica badge and the specific micro-contrast they claim, Sigma is gonna save you enough cash to fund another flight back there. The rendering is plenty good for prints, and unless you are staring at charts under a microscope, you wont notice the difference in the field. Make sure to pack a solid cleaning kit because the weather in Iceland is no joke, and you dont want to ruin an expensive piece of glass regardless of the brand.

Sigma Art glass is crazy sharp, but Leica has that unique look. For Iceland, consider the Sigma 24-70mm f/2.8 DG DN II Art if you want to save cash.

• Sharpness: Sigma wins
• Contrast: Leica