I don't know what you really mean by brightening. I don't do post processing, my computer doesn't have the horsepower (HP? lol) to handle RAW files. This is in-camera JPG. I did take a series of shots with different iso and exposure time. I forgot to try a smaller aperture at long exposure for possibly better sharpness.100 ISO is really too low because you need to brighten the image so much that you get more noise compared to shooting at a higher ISO that requires less image brightening. I shot at 2500 ISO and the image is not great either. Need a large sensor to capture more photons and a tracker for a good result without noise.
Below is a crop from a high iso setting with shorter exposure from that same shoot. Very noisy. I was going for an image that had the same overall "brightness" as seen live - give or take a half stop. In comparison my Wife's new semi-pro Canon EOS R7 has low noise at high iso.