Originally posted by Aaron28 side note: have not used the on board interval on the K-1 but have on others......the shortest time between shots is 2 seconds......if you expose for 30 seconds the interval time is 32
I don't bother with the interval shooting option. Instead I put the camera into the high continuous shooting mode and with my release cable I just flip a switch and let it shoot until I am sick of being out. There is less of a delay between shots doing it this way and you don't have to worry about going and resetting things or interrupting the interval shooting process. At this point you would need to figure out if you want trails or no trails and adjust your times from there. I usually prefer to have each shot capture no trails so I will have my shutter speed at 200/(focal length) as that will give the most options for combining things in post processing. Fast lenses are key and the suggestion of shooting at f/8 is one I would advise against as you likely won't need the depth of field offered since apart from the foreground object everything else will be at infinity. So with even with a 50mm lens everything will very likely already be basically at infinity or very close. However I do suggest stopping down some to clean up various chromatic aberrations and color fringing. Most of the Pentax 50/1.4 lenses do really well with astro if you stop them down to somewhere between f/2 and f/2.8, the SMC A 50/1.2 you can run at f/1.8 for pretty good results but at f/2 it is outstanding for astro. For things wider than that I have the S-M-C 28/3.5 Takumar which needs to be run at the half stop click between f/4 and f/5.6 to be usable for astro. I also have the DA AL 35/2.4 which is pretty good wide open but does bloat stars a lot there so you would want to stop it down 1 to 1.5 stops to clean it up. It isn't bad at f/3.5 which
is what I captured this at and I really didn't know what I was doing at that point. Going wider still I have the S-M-C 17mm f/4 fisheye Takumar which is unusable for astrophotography, and the Laowa 12mm f/2.8 which really good wide open but it does have some slight coma that doesn't go away until you hit f/4 but at f/4 it is great.
I see the subject of dark frames has come up and the advise was to take you own at the end. This is good and you will get better results by doing dark frame subtraction form each light frame with a master dark created from the session, instead of using the in camera dark frame subtraction.
Also capture as raw, photons are sparse when doing astro so the last thing you want to do is throw away close to half of your usable bits right away by shooting jpg.