>>2967439the rokinon 135mm is a great lens i have used it a bit to shoot some parts of the sky but its not ideal for deepsky objects. Stuff like north America nebula and maybe Andromeda are good for it, also consider if you can find modified dlsr without the IR filter, that gives you so much more objects to shoot.
What comes for the astrotracer on pentax cameras. It works but sometimes you have to calibrate the camera multiple times for it work perfectly.
Also see if theres any local observatories nearby. They might have some decent telescopes for you to use and are generally in dark location. I have one nearby and its like 25€/year to join the club and use the telescopes there.
Heres north America nebula taken with samyang/rokinon 135mm f2 using astrotracer on K1.
