Originally posted by mikeSF do you have astrotracer?
It looks like they do as the EXIF says it was taken with a K-3ii. I second this suggestion. Depending on which direction you have the camera pointed you might be able to get to a 2 minute exposure with that lens without issues. Pointing it north would likely show more trailing in the corners since astro tracer doesn't do rotation only x/y movement but when you are that wide it still shouldn't be too much of a problem.
Shooting at f/8 is basically a no no for astro photography and typically I will only stop the lens down .5 to 1 stop unless it is one of my really old ones that needs more to overcome the fringing problems it has. Then with those I stack the images to drive down the noise.
For something like this I would say the best approach would be to do it as several shots. Do 4 to 8 with astrotracer at ISO 400, 60-90s each (120 if you don't get bad trailing in the corners), at f/4 to f/5.6. Then stack them (use something like DeepSkyStacker as it does a good job with stars) and bring out the detail in the sky and ignore the blury foreground. Then I would do a few non-astrotracer shot for the foreground until I got the right exposure. Then I would combine the starfield with the foreground for the actual final image.
Man I would kill for a night sky like that. At 60 seconds at f/2.8 ISO400 (I think those are the settings I used) with the plastic fantastic 35mm f/2.4 in the dark place near me I have to do a lot of post processing to bring out any detail in the milky way. When I look up at the sky there it appears as a strip of slightly higher star density.