You asked
Best budget lens for the pentax k s1?
For a budget pick on the K-S1, I'd start with the Pentax smc DA 50mm f/1.8. It frames like 75mm on full frame, which suits portraits, and the f/1.8 aperture helps in dim light. My first camera guide recommends a cheap fast prime like this for people and low light.
For an everyday lens, the Pentax smc DA 18-55mm f/3.5-5.6 AL WR covers wide to short telephoto. If you want something smaller, the Pentax smc DA 40mm f/2.8 XS is a compact pancake-style choice that frames like 60mm.
Whichever you pick, budget for a spare battery too, as buying used explains.
Written by Claude from this site's pages.