You asked
Is the panasonic lumix s 18 40mm f 4 5 6 3 good for vlogging?
It can work, with caveats. The vlogging guide wants a lens around 16-20mm full-frame equivalent at arm's length, and this one starts at 18mm on full frame, so the wide end is close to right. On an APS-C body it frames like 27-60mm, which is too tight for most vlogging, so pair it with a full-frame camera.
Two things count against it. It isn't stabilised, which matters when you hold the camera at arm's length for minutes. And its aperture drops to f/4.5-6.3 as you zoom, so it's dim in low light. Sound matters more than the lens for vlogging, so budget for a microphone too, as the video guide suggests.
If you want to try it, these cameras take it on full frame:
For the full checklist of what makes a good vlogging setup, see the vlogging section.
Written by Claude from this site's pages.