Hello everyone,
Have read a lot in this great forum but not posted yet. I can contribute some experience by upgrading from K3-ii to K3-iii recently, I find this camera really amazing. Recently, I tried some astrophotography using the smc PENTAX-DA★300mmF4ED[IF] SDM together with the external GPS for Astrotracer.
Attached is Andromeda M31 from 8 frames stacked using DeepSkyStacker, 20s at ISO 6400; didn't do any post processing in Photoshop, just some curves to enhance the galaxy arms, but still noise is quite low, I think. I'm very, VERY happy with the sharpness of this lens at F4 (I bought it with the K3-iii) and with the performance of Astrotracer! Full size image can be found on flickr:
M31_stack8_6400_20s_full | Picture saved with settings embed? | Flickr