Focus a Third of the Way Into the Scene
Once you have decided your long exposure photography composition, the first thing that you should do is to set your focus point. For a landscape shot your lens will be set to an aperture value of f/10 or f/11. You should try not to go over f/16 to not stumble on diffraction problems.
Don’t use aperture to make a shot last longer. If you think that your shutter speed is not slow enough…well, this is where ND filters helps a lot.
You can try this simple trick to be sure of your focus point. You can try to focus on one of the two lower intersection points of the rule of thirds.
At this point, set the manual focus, so you do not have to change it anymore.
When it comes to long exposure photography composition, focusing is the most important part of your final photo. Better spend a lot of time to be sure of your point of focus than regret it later.
There’s nothing worse than going home and having an exposed photo for 1 or 2 minutes that’s totally out of focus.