Lenses these days have all kinds of aperture ranges, with some opening as wide as f/0.95 and others stopping down as much as f/32. But shooting at either extreme can cause potential issues. At the wider apertures, those issues are obvious. The shallower depth of field can mean you don’t get enough focus to get everything you need looking sharp. And most lenses are a little soft wide open anyway. Then as we stop them down, things get sharper. But is there a limit?
Well, yes. With many lenses, as you start to go past f/11, you’ll see things will become soft again. This is due to something called diffraction. We’ve covered diffraction here on DIYP before, a couple of times, actually, but it’s always good to have a reminder, and this video from Matt Granger does exactly that, explaining what diffraction is, what causes it and how you can prevent it (by basically not stopping down smaller than f/11).