You asked

Best travel lens for the sony a7s?

For travel on the Sony a7S, I'd start with the Sony FE 24-105mm f/4 G OSS. It covers wide streets, food, and people with one lens, and its OSS stabilisation matters because the a7S has none in the body. That's important for dim churches and interiors.

If you want something smaller, the Sony Vario-Tessar T* FE 24-70mm f/4 ZA OSS is a stabilised standard zoom that gives you a little less reach, and the Sony FE 28-60mm f/4-5.6 is a compact option for a bag that's already full.

For the "one small fast prime" that the travel kit guide recommends, I'd pick the Sony FE 24mm f/2.8 G for evenings and food.

Written by Claude from this site's pages.

From these pages