>>11910108What kind of camera do you have?
In case of my Canon EOS 2000D, I can get a life-view on the screen and enlarge it 10x.
I just point it at a star through the viewfinder, switch to life view, center it, enlarge it 5x, center it, enlarge it 10x, focus to get it as small as possible and done.
Though I can eyeball it through the viewfinder even though I have astigmatism and myopia.
The trick is not to look where it's sharp, but where the middle between focused too far and too close is.
If that's not an option because your camera can't do life-view and your eyes are too bad for an optical viewfinder, you can max out your cameras ISO, open the aperture fully, take sample shots and review them to see when you are in focus.
That might take 5 minutes, but it works.
With film you can only use the optical viewfinder and built in focus aids like the split-prism or microprisms, but with film your exposure times might get a little long as they don't realy make good high ISO film and the Schwarzschild exponent starts to be an issue...
