You asked
Voigtl nder color skopar 18mm f 2 8 aspherical vs 7artisans 18mm f 6 3 ii?
The two lenses frame the same way on APS-C: both are 18mm, which works out to about 27mm on full frame. The difference is how much light they let in.
The Voigtländer Color-Skopar 18mm f/2.8 Aspherical opens more than two stops wider. That means brighter pictures indoors and in the evening, and more background blur. It only mounts on Fujifilm X, though.
The 7Artisans 18mm f/6.3 II is a flat pancake that rarely needs more than a pocket. It also fits Sony E, Nikon Z and Micro Four Thirds, so it's the easier pick if you use a different system or want something you'll always carry.
Both are manual focus. If you shoot Fujifilm and want the brighter lens, I'd go with the Voigtländer. For everything else, the 7Artisans. For the basics on what the f-number does, see Lenses.
Written by Claude from this site's pages.