Dear Dr. Boli: For the first time, I have a camera with manual focus, and I’m still trying to figure it out. I’ve read the manual from cover to cover, but it doesn’t seem to deal with everything. Like I noticed one thing, and to be honest it’s kind of freaking me out. The focus has a setting for infinity. I’m not kidding: it says ∞ right there. So what will I see if I focus on infinity? I mean, just saying it gives me the willies. —Sincerely, A Photographer Who’s Never Used Anything More Complicated than an iPhone.
Dear Sir or Madam: For the love of all that is holy, please, please do not focus on infinity! Your mind is not equipped to survive the things you will see if you do. There are some secrets the universe is intent on keeping from us, and madness is the inevitable result of prying into them.
Ha ha! Dr. Boli is having a little fun at your expense. Actually, if you focus on infinity, you will see Cleveland. This is a curious but well-known fact of optics. The setting is really of use only to photographers in northeastern Ohio, but for them it comes in quite handy.