This is what is known as "a counsel of perfection"! Try to forget it, and take the same shot with different ISO settings, to see what difference you notice. There are some examples here.
The noise that one sees at high ISO only shows up in the dark areas of the scene. I dont think I have seen examples of such scenes in your photos posted here. As I have written before, "digital film" is free, so experiment. Most of us are not taking photos of UFOs and can afford the opportunity of retaking the shot!
If you are really worried about noise at high ISO, shoot raw files and process with DXO Photolab, as I do. (It is on Black Friday sale for another couple of days.)
I am preparing to post photos of Christmas Markets and Lighting taken almost in the dark, at ISO values up to 25,600.
Here is an example of one I took that night, simply for technical interest.
The deliberately underexposed jpeg out of the camera:
I think you'll agree that from the point of view of noise it is OK. I have to look carefully to see any.
The raw file, processed in Photolab6:
But feel free to disagree with me! (By the way, I have no commercial connection with DXO, except as a paying customer.)
No. I live way out in the county 20 miles from the nearest town..
That's what I mentioned earlier about "irrespective of noise". One thing I read earlier said that photos get "flatter" as you raise the ISO. I'm trying to find out for myself if that's true. Proponents of this approach say that you should start out at base ISO and only raise ISO if you have to.
Is it better to use longer shutter speeds, low ISO and a tripod, or faster shutter speeds to overcome camera shake and, higher ISO's?
Which gives you a better image quality?
I don't know.
Up to now, I've always used Aperture Priority and Auto ISO and let the camera work it out. It's only lately that I've begun getting into Manual and Long Exposure techniques..
I can only tell you that, while I can hand hold as slow as 1/20sec, I normally set the aperture I want and use a minimum speed of 1/100sec, allowing the ISO to go as high as it wants.
That’s basically what I do.
Experiment away, and you will quickly find out what works for you.