Decreasing your shutter speed, more light-on-sensor, is the first order of business to clean up the sky. Food-for-thought for your next outing…
You’re absolutely right, though camera specs/parametres weren’t the best on my side.
In order to catch the invisible comet (it was so faint, I had to REALLY stare into the dark to see it as a tiny cloudy spot and only knew where to look because of astro-software I took with me) I had to use the biggest lens I had in my disposal - Canon 105mm f2.8.
Now, f2.8 isn’t bad by any means, but it’s not the brightest for starry night.
The air was hazy and light pollution on that low angle was big. Going under 1/5 and the light pollution was getting out of control, while my comet’s brightness remained almost the same.
The biggest obstacle was my tiny tripod that just couldn’t handle this lens, so was used more as a monopod. Anything under half a sec was out of the question.
All in all, I hope the air will be more dry next time and I will carry some real, heavy duty tripod with me. 